diff --git a/client/public/index.html b/client/public/index.html
index afae296..22295fe 100644
--- a/client/public/index.html
+++ b/client/public/index.html
@@ -29,6 +29,8 @@
   <body>
     <noscript>You need to enable JavaScript to run this app.</noscript>
     <div id="root"></div>
+    <div id="modal-root"></div>
+
     <!--
       This HTML file is a template.
       If you open it directly in the browser, you will see an empty page.
diff --git a/client/src/components/arena/arena.css b/client/src/components/arena/arena.css
new file mode 100644
index 0000000..23d6e1d
--- /dev/null
+++ b/client/src/components/arena/arena.css
@@ -0,0 +1,63 @@
+.arena___root {
+  display: flex;
+  flex-direction: column;
+  justify-content: space-between;
+  width: 100%;
+  height: 100%;
+  background-size: cover;
+  background-image: url('../../resources/arena.jpg');
+  background-repeat: no-repeat;
+  background-position: center;
+}
+
+.arena___battlefield {
+  display: flex;
+  justify-content: space-around;
+  margin-bottom: 60px;
+}
+
+.arena___right-fighter img {
+  transform: scaleX(-1);
+}
+
+.arena___fighter img {
+  height: 480px;
+}
+
+.arena___fight-status {
+  display: flex;
+  margin: 30px;
+  justify-content: center;
+}
+
+.arena___fighter-name {
+  color: black;
+  -webkit-text-fill-color: white;
+  -webkit-text-stroke-width: 1px;
+  font-size: 26px;
+  font-family: 'Arial Black';
+  font-weight: 700;
+}
+
+.arena___fighter-indicator {
+  width: 100%;
+  display: flex;
+  align-items: center;
+  flex-direction: column;
+  margin: 0 30px;
+}
+
+.arena___health-indicator {
+  width: 100%;
+  height: 25px;
+  border: 2px solid;
+  border-radius: 5px;
+  margin: 0 10px;
+  overflow: hidden;
+}
+
+.arena___health-bar {
+  height: 100%;
+  width: 100%;
+  background-color: #ebd759;
+}
diff --git a/client/src/components/arena/index.jsx b/client/src/components/arena/index.jsx
new file mode 100644
index 0000000..5a48144
--- /dev/null
+++ b/client/src/components/arena/index.jsx
@@ -0,0 +1,322 @@
+import React, { Component } from 'react';
+import './arena.css';
+import controls from '../../constants/controls';
+import Modal from '../modal';
+
+const {
+  PlayerOneAttack,
+  PlayerOneBlock,
+  PlayerTwoAttack,
+  PlayerTwoBlock,
+  PlayerOneCriticalHitCombination: crit1,
+  PlayerTwoCriticalHitCombination: crit2,
+} = controls;
+
+// ******************************************
+
+class Arena extends Component {
+  //
+  playerOne = this.props.rivals.fighter1;
+  playerTwo = this.props.rivals.fighter2;
+
+  playerOneInitialHealth = this.playerOne.health;
+  playerTwoInitialHealth = this.playerTwo.health;
+
+  coolDownInterval = 10000;
+  events = ['keydown', 'keyup'];
+
+  state = {
+    pressedCombo1Keys: [],
+    pressedCombo2Keys: [],
+
+    playerOneCoolDown: false,
+    playerTwoCoolDown: false,
+
+    playerOneBlocks: false,
+    playerTwoBlocks: false,
+
+    playerOneHealth: this.playerOneInitialHealth,
+    playerTwoHealth: this.playerTwoInitialHealth,
+
+    winner: null,
+    showModal: false,
+  };
+
+  // **************** Lifecycle ****************
+
+  componentDidMount() {
+    this.events.forEach((eventType) =>
+      document.addEventListener(eventType, this.keyPressHandler)
+    );
+  }
+
+  componentDidUpdate(_, prevState) {
+    const { playerOneHealth, playerTwoHealth } = this.state;
+
+    const playerOneHealthBar = document.querySelector(
+      `#left-fighter-indicator`
+    );
+    const playerTwoHealthBar = document.querySelector(
+      `#right-fighter-indicator`
+    );
+
+    let winner = null;
+
+    if (prevState.playerOneHealth !== playerOneHealth) {
+      if (playerOneHealth > 0) {
+        playerOneHealthBar.style.width = `${
+          (playerOneHealth * 100) / this.playerOneInitialHealth
+        }%`;
+      } else {
+        playerOneHealthBar.style.width = '0%';
+        winner = this.playerTwo.name;
+      }
+    }
+
+    if (prevState.playerTwoHealth !== playerTwoHealth) {
+      if (playerTwoHealth > 0) {
+        playerTwoHealthBar.style.width = `${
+          (playerTwoHealth * 100) / this.playerTwoInitialHealth
+        }%`;
+      } else {
+        playerTwoHealthBar.style.width = '0%';
+        winner = this.playerOne.name;
+      }
+    }
+
+    if (winner) {
+      this.setState({ winner });
+      this.setState({ showModal: true });
+    }
+  }
+
+  componentWillUnmount() {
+    this.events.forEach((eventType) =>
+      document.removeEventListener(eventType, this.keyPressHandler)
+    );
+  }
+
+  // **************** Methods ****************
+
+  getChance(min, max) {
+    return Math.random() * (max - min) + min;
+  }
+
+  getHitPower(player) {
+    const criticalHitChance = this.getChance(1, 2);
+    const hitPower = (player.power / 10) * criticalHitChance;
+
+    return hitPower;
+  }
+
+  getBlockPower(player) {
+    const dodgeChance = this.getChance(1, 2);
+    const blockPower = player.defense * dodgeChance;
+
+    return blockPower;
+  }
+
+  getDamage(attacker, defender) {
+    let damage;
+
+    const hitPower = this.getHitPower(attacker);
+    const blockPower = this.getBlockPower(defender);
+
+    if (hitPower > blockPower) {
+      damage = hitPower - blockPower;
+    } else {
+      damage = 0;
+    }
+
+    return damage;
+  }
+
+  keyPressHandler = (event) => {
+    const playerOne = this.playerOne;
+    const playerTwo = this.playerTwo;
+    const coolDownInterval = this.coolDownInterval;
+
+    const {
+      pressedCombo1Keys,
+      pressedCombo2Keys,
+      playerOneCoolDown,
+      playerTwoCoolDown,
+      playerOneBlocks,
+      playerTwoBlocks,
+    } = this.state;
+
+    const { type, code, repeat } = event;
+
+    if (repeat) return;
+
+    if (type === 'keydown') {
+      //
+      // Player 1 combo
+      const oneOfCombo1 =
+        code === crit1[0] || code === crit1[1] || code === crit1[2];
+
+      if (
+        !playerOneCoolDown &&
+        oneOfCombo1 &&
+        !pressedCombo1Keys.includes(code)
+      ) {
+        this.setState((prevState) => {
+          return { pressedCombo1Keys: prevState.pressedCombo1Keys.push(code) };
+        });
+      }
+
+      if (pressedCombo1Keys.length === 3) {
+        const damage = playerOne.attack * 2;
+        this.healthIndicatorUpdater(playerOne, damage);
+        this.setState({ pressedCombo1Keys: [] });
+
+        this.setState({ playerOneCoolDown: true });
+
+        setTimeout(() => {
+          this.setState({ playerOneCoolDown: false });
+        }, coolDownInterval);
+      }
+
+      // Player 2 combo
+      const oneOfCombo2 =
+        code === crit2[0] || code === crit2[1] || code === crit2[2];
+
+      if (
+        !playerTwoCoolDown &&
+        oneOfCombo2 &&
+        !pressedCombo2Keys.includes(code)
+      ) {
+        this.setState((prevState) => {
+          return { pressedCombo2Keys: prevState.pressedCombo2Keys.push(code) };
+        });
+      }
+
+      if (pressedCombo2Keys.length === 3) {
+        const damage = playerTwo.attack * 2;
+        this.healthIndicatorUpdater(playerTwo, damage);
+        this.setState({ pressedCombo2Keys: [] });
+
+        this.setState({ playerTwoCoolDown: true });
+
+        setTimeout(() => {
+          this.setState({ playerTwoCoolDown: false });
+        }, coolDownInterval);
+      }
+
+      // Player 1 regular attack
+      if (!playerOneBlocks && code === PlayerOneAttack) {
+        const damage = playerTwoBlocks
+          ? this.getDamage(playerOne, playerTwo)
+          : this.getHitPower(playerOne);
+
+        this.setState((prevState) => {
+          return { playerTwoHealth: prevState.playerTwoHealth - damage };
+        });
+      }
+
+      // Player 2 regular attack
+      if (!playerTwoBlocks && code === PlayerTwoAttack) {
+        const damage = playerTwoBlocks
+          ? this.getDamage(playerTwo, playerOne)
+          : this.getHitPower(playerTwo);
+
+        this.setState((prevState) => {
+          return { playerOneHealth: prevState.playerOneHealth - damage };
+        });
+      }
+
+      // Blocks
+      if (code === PlayerOneBlock) this.setState({ playerOneBlocks: true });
+      if (code === PlayerTwoBlock) this.setState({ playerTwoBlocks: true });
+    }
+
+    if (type === 'keyup') {
+      //
+      // Remove key code from the combo log on keyup - player 1
+      if (pressedCombo1Keys.includes(code)) {
+        const index = pressedCombo1Keys.indexOf(code);
+
+        this.setState((prevState) => {
+          return {
+            pressedCombo1Keys: prevState.pressedCombo1Keys.splice(index, 1),
+          };
+        });
+      }
+
+      // Remove key code from the combo log on keyup - player 2
+      if (pressedCombo2Keys.includes(code)) {
+        const index = pressedCombo2Keys.indexOf(code);
+
+        this.setState((prevState) => {
+          return {
+            pressedCombo2Keys: prevState.pressedCombo2Keys.splice(index, 1),
+          };
+        });
+      }
+
+      if (code === PlayerOneBlock) this.setState({ playerOneBlocks: false });
+      if (code === PlayerTwoBlock) this.setState({ PlayerTwoBlocks: false });
+    }
+  };
+
+  // **************** Render ****************
+
+  render() {
+    const { fighter1, fighter2 } = this.props.rivals;
+    const { showModal, winner } = this.state;
+
+    return (
+      <div className="arena___root">
+        {showModal && <Modal winner={winner} onClose={this.props.onGameOver} />}
+
+        <div className="arena___fight-status">
+          {/*  */}
+          <div className="arena___fighter-indicator">
+            <span className="arena___fighter-name">{fighter1.name}</span>
+            <div className="arena___health-indicator">
+              <div
+                className="arena___health-bar"
+                id="left-fighter-indicator"
+              ></div>
+            </div>
+          </div>
+
+          <div className="arena___versus-sign"></div>
+
+          <div className="arena___fighter-indicator">
+            <span className="arena___fighter-name">{fighter2.name}</span>
+            <div className="arena___health-indicator">
+              <div
+                className="arena___health-bar"
+                id="right-fighter-indicator"
+              ></div>
+            </div>
+          </div>
+        </div>
+
+        <div className="arena___battlefield">
+          {/*  */}
+          <div className="arena___fighter arena___left-fighter">
+            <img
+              className="fighter-preview___img"
+              src={fighter1.source}
+              title={fighter1.name}
+              alt={fighter1.name}
+            />
+          </div>
+
+          <div className="arena___fighter arena___right-fighter">
+            <img
+              className="fighter-preview___img"
+              src={fighter2.source}
+              title={fighter2.name}
+              alt={fighter2.name}
+            />
+          </div>
+        </div>
+      </div>
+    );
+  }
+}
+
+export default Arena;
diff --git a/client/src/components/fight/fight.css b/client/src/components/fight/fight.css
index 556847e..21e8d48 100644
--- a/client/src/components/fight/fight.css
+++ b/client/src/components/fight/fight.css
@@ -1,22 +1,23 @@
 #wrapper {
-    margin-top: 2rem;
+  margin-top: 2rem;
 }
 
-#figh-wrapper {
-    width: 70%;
-    margin: 2rem auto;
-    border: 1px solid rgba(0,0,0,0.1);
-    display: flex;
+#fight-wrapper {
+  width: 70%;
+  margin: 2rem auto;
+  border: 1px solid rgba(0, 0, 0, 0.1);
+  display: flex;
 }
 
-#figh-wrapper > *:first-child, #figh-wrapper > *:last-child {
-    flex: 1;
+#fight-wrapper > *:first-child,
+#fight-wrapper > *:last-child {
+  flex: 1;
 }
 
 .btn-wrapper {
-    margin: 0 1rem;
-    display: flex;
-    align-items: flex-start;
-    padding-top: 1rem;
-    justify-content: center;
-}
\ No newline at end of file
+  margin: 0 1rem;
+  display: flex;
+  align-items: flex-start;
+  padding-top: 1rem;
+  justify-content: center;
+}
diff --git a/client/src/components/fight/index.jsx b/client/src/components/fight/index.jsx
index 4fc8bdd..a8c922e 100644
--- a/client/src/components/fight/index.jsx
+++ b/client/src/components/fight/index.jsx
@@ -4,72 +4,119 @@ import { getFighters } from '../../services/domainRequest/fightersRequest';
 import NewFighter from '../newFighter';
 import Fighter from '../fighter';
 import { Button } from '@material-ui/core';
+import './fight.css';
+import Arena from '../arena';
 
-import './fight.css'
+// ******************************************
 
 class Fight extends React.Component {
-    state = {
-        fighters: [],
-        fighter1: null,
-        fighter2: null
-    };
-
-    async componentDidMount() {
-        const fighters = await getFighters();
-        if(fighters && !fighters.error) {
-            this.setState({ fighters });
-        }
-    }
+  state = {
+    fighters: [],
+    fighter1: null,
+    fighter2: null,
+    rivals: null,
+    fightStarted: false,
+  };
 
-    onFightStart = () => {
-        
-    }
+  //  **************** Lifecycle ****************
 
-    onCreate = (fighter) => {
-        this.setState({ fighters: [...this.state.fighters, fighter] });
-    }
+  async componentDidMount() {
+    const fighters = await getFighters();
+    const error = 'Connection with server failed. \nPlease try again later';
 
-    onFighter1Select = (fighter1) => {
-        this.setState({fighter1 });
+    if (fighters && !fighters.error) {
+      this.setState({ fighters });
+    } else {
+      alert(error);
     }
+  }
+
+  // **************** Methods ****************
 
-    onFighter2Select = (fighter2) => {
-        this.setState({ fighter2 });
+  onFightStart = () => {
+    const { fighter1, fighter2 } = this.state;
+
+    if (fighter1 && fighter2) {
+      this.setState({
+        rivals: { fighter1, fighter2 },
+      });
+    } else {
+      alert('Please select both fighters');
     }
+  };
+
+  onCreate = (fighter) => {
+    this.setState({ fighters: [...this.state.fighters, fighter] });
+  };
+
+  onFighter1Select = (fighter1) => {
+    this.setState({ fighter1 });
+  };
 
-    getFighter1List = () => {
-        const { fighter2, fighters } = this.state;
-        if(!fighter2) {
-            return fighters;
-        }
+  onFighter2Select = (fighter2) => {
+    this.setState({ fighter2 });
+  };
 
-        return fighters.filter(it => it.id !== fighter2.id);
+  getFighter1List = () => {
+    const { fighter2, fighters } = this.state;
+    if (!fighter2) {
+      return fighters;
     }
 
-    getFighter2List = () => {
-        const { fighter1, fighters } = this.state;
-        if(!fighter1) {
-            return fighters;
-        }
+    return fighters.filter((it) => it.id !== fighter2.id);
+  };
 
-        return fighters.filter(it => it.id !== fighter1.id);
+  getFighter2List = () => {
+    const { fighter1, fighters } = this.state;
+    if (!fighter1) {
+      return fighters;
     }
 
-    render() {
-        const  { fighter1, fighter2 } = this.state;
-        return (
-            <div id="wrapper">
-                <NewFighter onCreated={this.onCreate} />
-                <div id="figh-wrapper">
-                    <Fighter selectedFighter={fighter1} onFighterSelect={this.onFighter1Select} fightersList={this.getFighter1List() || []} />
-                    <div className="btn-wrapper">
-                        <Button onClick={this.onFightStart} variant="contained" color="primary">Start Fight</Button>
-                    </div>
-                    <Fighter selectedFighter={fighter2} onFighterSelect={this.onFighter2Select} fightersList={this.getFighter2List() || []} />
-                </div>
-            </div>
-        );
+    return fighters.filter((it) => it.id !== fighter1.id);
+  };
+
+  onGameOver = () => {
+    this.setState({ rivals: null });
+  };
+
+  // **************** Render ****************
+
+  render() {
+    const { fighter1, fighter2, rivals } = this.state;
+
+    if (rivals) {
+      return <Arena rivals={rivals} onGameOver={this.onGameOver} />;
     }
+
+    return (
+      <div id="wrapper">
+        <NewFighter onCreated={this.onCreate} />
+        <div id="fight-wrapper">
+          <Fighter
+            selectedFighter={fighter1}
+            onFighterSelect={this.onFighter1Select}
+            fightersList={this.getFighter1List() || []}
+          />
+
+          <div className="btn-wrapper">
+            <Button
+              onClick={this.onFightStart}
+              variant="contained"
+              color="primary"
+            >
+              Start Fight
+            </Button>
+          </div>
+
+          <Fighter
+            selectedFighter={fighter2}
+            onFighterSelect={this.onFighter2Select}
+            fightersList={this.getFighter2List() || []}
+          />
+        </div>
+      </div>
+    );
+  }
 }
 
-export default Fight;
\ No newline at end of file
+export default Fight;
diff --git a/client/src/components/fighter/index.jsx b/client/src/components/fighter/index.jsx
index cc4cd04..8fae0d3 100644
--- a/client/src/components/fighter/index.jsx
+++ b/client/src/components/fighter/index.jsx
@@ -3,50 +3,55 @@ import { FormControl, InputLabel, makeStyles, Select } from '@material-ui/core';
 import { MenuItem } from 'material-ui';
 
 const useStyles = makeStyles((theme) => ({
-    formControl: {
-        margin: theme.spacing(1),
-        minWidth: 120,
-    },
-    selectEmpty: {
-        marginTop: theme.spacing(2),
-    },
+  formControl: {
+    margin: theme.spacing(1),
+    minWidth: 120,
+  },
+  selectEmpty: {
+    marginTop: theme.spacing(2),
+  },
 }));
 
-export default function Fighter({ fightersList, onFighterSelect, selectedFighter }) {
-    const classes = useStyles();
-    const [fighter, setFighter] = useState();
+export default function Fighter({
+  fightersList,
+  onFighterSelect,
+  selectedFighter,
+}) {
+  const classes = useStyles();
+  const [fighter, setFighter] = useState();
 
-    const handleChange = (event) => {
-        debugger;
-        setFighter(event.target.value);
-        onFighterSelect(event.target.value);
-    };
+  const handleChange = (event) => {
+    setFighter(event.target.value);
+    onFighterSelect(event.target.value);
+  };
 
-    return (
-        <div>
-            <FormControl className={classes.formControl}>
-                <InputLabel id="simple-select-label">Select Fighter</InputLabel>
-                <Select
-                    labelId="simple-select-label"
-                    id="simple-select"
-                    value={fighter}
-                    onChange={handleChange}
-                >
-                    {fightersList.map((it, index) => {
-                        return (
-                            <MenuItem key={`${index}`} value={it}>{it.name}</MenuItem>
-                        );
-                    })}
-                </Select>
-                {selectedFighter
-                    ? <div>
-                        <div>Name: {selectedFighter.name}</div>
-                        <div>Power: {selectedFighter.power}</div>
-                        <div>Defense: {selectedFighter.defense}</div>
-                        <div>Health: {selectedFighter.health}</div>
-                    </div>
-                    : null
-                }
-            </FormControl>
-        </div>)
+  return (
+    <div>
+      <FormControl className={classes.formControl}>
+        <InputLabel id="simple-select-label">Select Fighter</InputLabel>
+        <Select
+          labelId="simple-select-label"
+          id="simple-select"
+          value={fighter}
+          onChange={handleChange}
+        >
+          {fightersList.map((it, index) => {
+            return (
+              <MenuItem key={`${index}`} value={it}>
+                {it.name}
+              </MenuItem>
+            );
+          })}
+        </Select>
+        {selectedFighter ? (
+          <div>
+            <div>Name: {selectedFighter.name}</div>
+            <div>Power: {selectedFighter.power}</div>
+            <div>Defense: {selectedFighter.defense}</div>
+            <div>Health: {selectedFighter.health}</div>
+          </div>
+        ) : null}
+      </FormControl>
+    </div>
+  );
 }
diff --git a/client/src/components/modal/index.jsx b/client/src/components/modal/index.jsx
new file mode 100644
index 0000000..2247877
--- /dev/null
+++ b/client/src/components/modal/index.jsx
@@ -0,0 +1,57 @@
+import React, { Component } from 'react';
+import { createPortal } from 'react-dom';
+
+import './modal.css';
+
+// ***************************************
+
+const modalRoot = document.querySelector('#modal-root');
+// const modalRoot = document.querySelector('.arena___root');
+
+// ***************************************
+
+export default class Modal extends Component {
+  //
+  componentDidMount() {
+    window.addEventListener('keydown', this.handleKeydown);
+  }
+
+  componentWillUnmount() {
+    window.removeEventListener('keydown', this.handleKeydown);
+  }
+
+  handleKeydown = (event) => {
+    if (event.code === 'Escape') {
+      this.props.onClose();
+    }
+  };
+
+  handleBackdropClick = (event) => {
+    if (event.target === event.currentTarget) {
+      this.props.onClose();
+    }
+  };
+
+  onClose = () => {
+    alert('Modal closed, thank you');
+  };
+
+  render() {
+    const { winner } = this.props;
+
+    return createPortal(
+      <div className="modal-overlay" onClick={this.handleBackdropClick}>
+        <div className="modal-root">
+          <div className="modal-header">
+            <span>Game over</span>
+            <div className="close-btn" onClick={this.props.onClose}>
+              ×
+            </div>
+          </div>
+          <div className="modal-body">{winner} wins</div>
+        </div>
+      </div>,
+      modalRoot
+    );
+  }
+}
diff --git a/client/src/components/modal/modal.css b/client/src/components/modal/modal.css
new file mode 100644
index 0000000..d042ceb
--- /dev/null
+++ b/client/src/components/modal/modal.css
@@ -0,0 +1,61 @@
+.modal-overlay {
+  position: fixed;
+  top: 0;
+  left: 0;
+  width: 100vw;
+  height: 100vh;
+  display: flex;
+  justify-content: center;
+  align-items: center;
+  background-color: rgba(250, 0, 0, 0.2);
+  z-index: 1200;
+
+  backdrop-filter: blur(10px);
+}
+
+.modal-root {
+  display: flex;
+  flex-direction: column;
+  border: 3px solid black;
+  background-color: steelblue;
+  background-image: url('../../resources/arena.jpg');
+  background-position: center;
+  background-size: cover;
+
+  border-radius: 12px;
+  overflow: hidden;
+}
+
+.modal-header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  min-width: 300px;
+  padding: 1rem;
+  font-weight: 700;
+  font-size: 26px;
+
+  background-color: black;
+  color: white;
+}
+
+.modal-body {
+  padding: 4rem;
+
+  font-family: Arial, Helvetica, sans-serif;
+  text-shadow: 2px 2px 25px black, -2px -2px 25px black;
+  font-size: 5rem;
+  font-weight: bold;
+  text-transform: uppercase;
+
+  color: orangered;
+  text-align: center;
+}
+
+.close-btn {
+  font-size: 1.5rem;
+  font-weight: 700;
+  line-height: 1;
+
+  cursor: pointer;
+}
diff --git a/client/src/components/newFighter/index.jsx b/client/src/components/newFighter/index.jsx
index 3848288..7507792 100644
--- a/client/src/components/newFighter/index.jsx
+++ b/client/src/components/newFighter/index.jsx
@@ -1,42 +1,67 @@
-import { TextField } from "material-ui"
-import { createFighter } from "../../services/domainRequest/fightersRequest";
-import React, { useState } from "react";
-import { Button } from "@material-ui/core";
+import { TextField } from 'material-ui';
+import { createFighter } from '../../services/domainRequest/fightersRequest';
+import React, { useState } from 'react';
+import { Button } from '@material-ui/core';
 import './newFighter.css';
 
 export default function NewFighter({ onCreated }) {
-    const [name, setName] = useState();
-    const [power, setPower] = useState();
-    const [defense, setDefense] = useState();
+  const [name, setName] = useState();
+  const [power, setPower] = useState();
+  const [defense, setDefense] = useState();
 
-    const onNameChange = (event) => {
-        setName(event.target.value);
-    }
+  const onNameChange = (event) => {
+    setName(event.target.value);
+  };
 
-    const onPowerChange = (event) => {
-        const value = event.target.value || event.target.value === 0 ? Number(event.target.value) : null;
-        setPower(value);
-    }
+  const onPowerChange = (event) => {
+    const value =
+      event.target.value || event.target.value === 0
+        ? Number(event.target.value)
+        : null;
+    setPower(value);
+  };
 
-    const onDefenseChange = (event) => {
-        const value = event.target.value || event.target.value === 0 ? Number(event.target.value) : null;
-        setDefense(value);
-    }
+  const onDefenseChange = (event) => {
+    const value =
+      event.target.value || event.target.value === 0
+        ? Number(event.target.value)
+        : null;
+    setDefense(value);
+  };
 
-    const onSubmit = async () => {
-        const data = await createFighter({ name, power, defense });
-        if(data && !data.error) {
-            onCreated(data);
-        }
+  const onSubmit = async () => {
+    const data = await createFighter({ name, power, defense });
+    if (data && !data.error) {
+      onCreated(data);
     }
+  };
 
-    return (
-        <div id="new-fighter">
-            <div>New Fighter</div>
-            <TextField onChange={onNameChange} id="standard-basic" label="Standard" placeholder="Name"/>
-            <TextField onChange={onPowerChange} id="standard-basic" label="Standard" placeholder="Power" type="number" />
-            <TextField onChange={onDefenseChange} id="standard-basic" label="Standard" placeholder="Defense" type="number" />
-            <Button onClick={onSubmit} variant="contained" color="primary">Create</Button>
-        </div>
-    );
-};
\ No newline at end of file
+  return (
+    <div id="new-fighter">
+      <div>New Fighter</div>
+      <TextField
+        onChange={onNameChange}
+        id="standard-basic"
+        label="Standard"
+        placeholder="Name"
+      />
+      <TextField
+        onChange={onPowerChange}
+        id="standard-basic"
+        label="Standard"
+        placeholder="Power"
+        type="number"
+      />
+      <TextField
+        onChange={onDefenseChange}
+        id="standard-basic"
+        label="Standard"
+        placeholder="Defense"
+        type="number"
+      />
+      <Button onClick={onSubmit} variant="contained" color="primary">
+        Create
+      </Button>
+    </div>
+  );
+}
diff --git a/client/src/components/signIn/index.jsx b/client/src/components/signIn/index.jsx
index ca8f45b..62add66 100644
--- a/client/src/components/signIn/index.jsx
+++ b/client/src/components/signIn/index.jsx
@@ -8,40 +8,54 @@ import { login } from '../../services/domainRequest/auth';
 import { setLoginSession } from '../../services/authService';
 
 const useStyles = makeStyles((theme) => ({
-    root: {
-        '& > *': {
-            margin: theme.spacing(1),
-            width: '25ch',
-        },
+  root: {
+    '& > *': {
+      margin: theme.spacing(1),
+      width: '25ch',
     },
+  },
 }));
 
 export default function SignIn({ setIsLoggedIn }) {
-    const classes = useStyles();
-    const [email, setEmail] = useState();
-    const [password, setPassword] = useState();
+  const classes = useStyles();
+  const [email, setEmail] = useState();
+  const [password, setPassword] = useState();
 
-    const onEmailChange = (event) => {
-        setEmail(event.target.value);
-    }
+  const onEmailChange = (event) => {
+    setEmail(event.target.value);
+  };
 
-    const onPasswordChange = (event) => {
-        setPassword(event.target.value);
-    }
+  const onPasswordChange = (event) => {
+    setPassword(event.target.value);
+  };
+
+  const onSubmit = async () => {
+    const data = await login({ email, password });
 
-    const onSubmit = async () => {
-        const data = await login({ email, password });
-        if(data && !data.error) {
-            setLoginSession(data);
-            setIsLoggedIn(true);
-        }
+    if (data && !data.error) {
+      setLoginSession(data);
+      setIsLoggedIn(true);
     }
+  };
 
-    return (
-        <form className={classes.root} noValidate autoComplete="off">
-            <TextField onChange={onEmailChange} id="standard-basic" label="Standard" placeholder="Email"/>
-            <TextField onChange={onPasswordChange} id="standard-basic" label="Standard" placeholder="Password" type="password"/>
-            <Button onClick={onSubmit} variant="contained" color="primary">Sign In</Button>
-        </form>
-    )
-}
\ No newline at end of file
+  return (
+    <form className={classes.root} noValidate autoComplete="off">
+      <TextField
+        onChange={onEmailChange}
+        id="standard-basic"
+        label="Standard"
+        placeholder="Email"
+      />
+      <TextField
+        onChange={onPasswordChange}
+        id="standard-basic"
+        label="Standard"
+        placeholder="Password"
+        type="password"
+      />
+      <Button onClick={onSubmit} variant="contained" color="primary">
+        Sign In
+      </Button>
+    </form>
+  );
+}
diff --git a/client/src/components/signIn/signIn.css b/client/src/components/signIn/signIn.css
index 3ee2b75..6807926 100644
--- a/client/src/components/signIn/signIn.css
+++ b/client/src/components/signIn/signIn.css
@@ -1,4 +1,4 @@
 form {
-    display: flex;
-    flex-direction: column;
-}
\ No newline at end of file
+  display: flex;
+  flex-direction: column;
+}
diff --git a/client/src/components/signInUpPage/index.jsx b/client/src/components/signInUpPage/index.jsx
index 4e585f8..f182d60 100644
--- a/client/src/components/signInUpPage/index.jsx
+++ b/client/src/components/signInUpPage/index.jsx
@@ -4,35 +4,48 @@ import SignIn from '../signIn';
 import SignUp from '../signUp';
 
 const signPages = {
-    signIn: 0,
-    signUp: 1
+  signIn: 0,
+  signUp: 1,
 };
 
 class SignInSignUpPage extends React.Component {
-    state = {
-        index: signPages.signUp
-    };
+  state = {
+    index: signPages.signUp,
+  };
 
-    setIndex = (index) => {
-        this.setState({ index });
-    }
+  setIndex = (index) => {
+    this.setState({ index });
+  };
 
-    render() {
-        const { index } = this.state;
+  render() {
+    const { index } = this.state;
 
-        return (
-            <div id="sign-in-up">
-                <div id="form-wrapper">
-                    <div className="header">
-                        <div onClick={() => this.setIndex(signPages.signIn)} className={`${index === signPages.signIn ? 'active' : ''}`}>Sign In</div>
-                        <div onClick={() => this.setIndex(signPages.signUp)} className={`${index === signPages.signUp ? 'active' : ''}`}>Sign Up</div>
-                    </div>
-                    {index === signPages.signIn ? <SignIn setIsLoggedIn={this.props.setIsLoggedIn} /> : <SignUp setIsLoggedIn={this.props.setIsLoggedIn}/>}
-                </div>
+    return (
+      <div id="sign-in-up">
+        <div id="form-wrapper">
+          <div className="header">
+            <div
+              onClick={() => this.setIndex(signPages.signIn)}
+              className={`${index === signPages.signIn ? 'active' : ''}`}
+            >
+              Sign In
             </div>
-        );
-    }
+            <div
+              onClick={() => this.setIndex(signPages.signUp)}
+              className={`${index === signPages.signUp ? 'active' : ''}`}
+            >
+              Sign Up
+            </div>
+          </div>
+          {index === signPages.signIn ? (
+            <SignIn setIsLoggedIn={this.props.setIsLoggedIn} />
+          ) : (
+            <SignUp setIsLoggedIn={this.props.setIsLoggedIn} />
+          )}
+        </div>
+      </div>
+    );
+  }
 }
 
-
-export default SignInSignUpPage;
\ No newline at end of file
+export default SignInSignUpPage;
diff --git a/client/src/components/signUp/index.jsx b/client/src/components/signUp/index.jsx
index fb70e8f..4a215e2 100644
--- a/client/src/components/signUp/index.jsx
+++ b/client/src/components/signUp/index.jsx
@@ -7,59 +7,97 @@ import { createUser } from '../../services/domainRequest/userRequest';
 import { setLoginSession } from '../../services/authService';
 
 const useStyles = makeStyles((theme) => ({
-    root: {
-        '& > *': {
-            margin: theme.spacing(1),
-            width: '25ch',
-        },
+  root: {
+    '& > *': {
+      margin: theme.spacing(1),
+      width: '25ch',
     },
+  },
 }));
 
 export default function SignUp({ setIsLoggedIn }) {
-    const classes = useStyles();
-    const [email, setEmail] = useState();
-    const [password, setPassword] = useState();
-    const [firstName, setFirstName] = useState();
-    const [lastName, setLastName] = useState();
-    const [phoneNumber, setPhoneNumber] = useState();
+  const classes = useStyles();
+  const [email, setEmail] = useState();
+  const [password, setPassword] = useState();
+  const [firstName, setFirstName] = useState();
+  const [lastName, setLastName] = useState();
+  const [phoneNumber, setPhoneNumber] = useState();
 
-    const onEmailChange = (event) => {
-        setEmail(event.target.value);
-    }
+  const onEmailChange = (event) => {
+    setEmail(event.target.value);
+  };
 
-    const onPasswordChange = (event) => {
-        setPassword(event.target.value);
-    }
+  const onPasswordChange = (event) => {
+    setPassword(event.target.value);
+  };
 
-    const onFirstNameChange = (event) => {
-        setFirstName(event.target.value);
-    }
+  const onFirstNameChange = (event) => {
+    setFirstName(event.target.value);
+  };
 
-    const onLastNameChange = (event) => {
-        setLastName(event.target.value);
-    }
+  const onLastNameChange = (event) => {
+    setLastName(event.target.value);
+  };
 
-    const onPhoneNumberChange = (event) => {
-        setPhoneNumber(event.target.value);
-    }
-    
+  const onPhoneNumberChange = (event) => {
+    setPhoneNumber(event.target.value);
+  };
 
-    const onSubmit = async () => {
-        const data = await createUser({ email, password, firstName, lastName, phoneNumber });
-        if(data && !data.error) {
-            setLoginSession(data);
-            setIsLoggedIn(true);
-        }
+  const onSubmit = async () => {
+    const data = await createUser({
+      email,
+      password,
+      firstName,
+      lastName,
+      phoneNumber,
+    });
+    if (data && !data.error) {
+      setLoginSession(data);
+      setIsLoggedIn(true);
     }
+  };
 
-    return (
-        <form className={classes.root} noValidate autoComplete="off">
-            <TextField key="first-name" onChange={onFirstNameChange} id="standard-basic" label="Standard" placeholder="First Name"/>
-            <TextField key="last-name" onChange={onLastNameChange} id="standard-basic" label="Standard" placeholder="Last Name"/>
-            <TextField key="email" onChange={onEmailChange} id="standard-basic" label="Standard" placeholder="Email"/>
-            <TextField key="phone" onChange={onPhoneNumberChange} id="standard-basic" label="Standard" placeholder="Phone Number"/>
-            <TextField key="password" onChange={onPasswordChange} id="standard-basic" label="Standard" placeholder="Password" type="password"/>
-            <Button onClick={onSubmit} variant="contained" color="primary">Sign Up</Button>
-        </form>
-    )
-}
\ No newline at end of file
+  return (
+    <form className={classes.root} noValidate autoComplete="off">
+      <TextField
+        key="first-name"
+        onChange={onFirstNameChange}
+        id="standard-basic"
+        label="Standard"
+        placeholder="First Name"
+      />
+      <TextField
+        key="last-name"
+        onChange={onLastNameChange}
+        id="standard-basic"
+        label="Standard"
+        placeholder="Last Name"
+      />
+      <TextField
+        key="email"
+        onChange={onEmailChange}
+        id="standard-basic"
+        label="Standard"
+        placeholder="Email"
+      />
+      <TextField
+        key="phone"
+        onChange={onPhoneNumberChange}
+        id="standard-basic"
+        label="Standard"
+        placeholder="Phone Number"
+      />
+      <TextField
+        key="password"
+        onChange={onPasswordChange}
+        id="standard-basic"
+        label="Standard"
+        placeholder="Password"
+        type="password"
+      />
+      <Button onClick={onSubmit} variant="contained" color="primary">
+        Sign Up
+      </Button>
+    </form>
+  );
+}
diff --git a/client/src/components/startScreen/index.jsx b/client/src/components/startScreen/index.jsx
index 24804e7..8ac88b3 100644
--- a/client/src/components/startScreen/index.jsx
+++ b/client/src/components/startScreen/index.jsx
@@ -5,31 +5,35 @@ import Fight from '../fight';
 import SignOut from '../signOut';
 
 class StartScreen extends React.Component {
-    state = {
-        isSignedIn: false
-    };
+  state = {
+    isSignedIn: false,
+  };
 
-    componentDidMount() {
-        this.setIsLoggedIn(isSignedIn());
-    }
+  componentDidMount() {
+    this.setIsLoggedIn(isSignedIn());
+  }
 
-    setIsLoggedIn = (isSignedIn) => {
-        this.setState({ isSignedIn });
-    }
+  setIsLoggedIn = (isSignedIn) => {
+    this.setState({ isSignedIn });
+  };
 
-    render() {
-        const { isSignedIn } = this.state;
-        if (!isSignedIn) {
-            return <SignInUpPage setIsLoggedIn={this.setIsLoggedIn} />
-        }
+  render() {
+    const { isSignedIn } = this.state;
 
-        return (
-            <>
-                <Fight />
-                <SignOut isSignedIn={isSignedIn} onSignOut={() => this.setIsLoggedIn(false)} />
-            </>
-        );
+    if (!isSignedIn) {
+      return <SignInUpPage setIsLoggedIn={this.setIsLoggedIn} />;
     }
+
+    return (
+      <>
+        <Fight />
+        <SignOut
+          isSignedIn={isSignedIn}
+          onSignOut={() => this.setIsLoggedIn(false)}
+        />
+      </>
+    );
+  }
 }
 
-export default StartScreen;
\ No newline at end of file
+export default StartScreen;
diff --git a/client/src/constants/controls.js b/client/src/constants/controls.js
new file mode 100644
index 0000000..ccdf88d
--- /dev/null
+++ b/client/src/constants/controls.js
@@ -0,0 +1,10 @@
+const controls = {
+    PlayerOneAttack: 'KeyA',
+    PlayerOneBlock: 'KeyD',
+    PlayerTwoAttack: 'KeyJ',
+    PlayerTwoBlock: 'KeyL',
+    PlayerOneCriticalHitCombination: ['KeyQ', 'KeyW', 'KeyE'],
+    PlayerTwoCriticalHitCombination: ['KeyU', 'KeyI', 'KeyO']
+};
+
+export default controls;
diff --git a/client/src/index.js b/client/src/index.js
index f5185c1..3c7fae3 100644
--- a/client/src/index.js
+++ b/client/src/index.js
@@ -14,4 +14,6 @@ ReactDOM.render(
 // If you want your app to work offline and load faster, you can change
 // unregister() to register() below. Note this comes with some pitfalls.
 // Learn more about service workers: https://bit.ly/CRA-PWA
-serviceWorker.unregister();
+
+// serviceWorker.unregister();
+serviceWorker.register();
diff --git a/client/src/resources/arena.jpg b/client/src/resources/arena.jpg
new file mode 100644
index 0000000..13820e9
Binary files /dev/null and b/client/src/resources/arena.jpg differ
diff --git a/client/src/resources/logo.png b/client/src/resources/logo.png
new file mode 100644
index 0000000..0865ffb
Binary files /dev/null and b/client/src/resources/logo.png differ
diff --git a/client/src/resources/main-bg.jpg b/client/src/resources/main-bg.jpg
new file mode 100644
index 0000000..9da031e
Binary files /dev/null and b/client/src/resources/main-bg.jpg differ
diff --git a/client/src/resources/versus.png b/client/src/resources/versus.png
new file mode 100644
index 0000000..c560bd3
Binary files /dev/null and b/client/src/resources/versus.png differ
diff --git a/client/src/services/domainRequest/userRequest.js b/client/src/services/domainRequest/userRequest.js
index 0f273e1..c4c19ed 100644
--- a/client/src/services/domainRequest/userRequest.js
+++ b/client/src/services/domainRequest/userRequest.js
@@ -1,6 +1,6 @@
-import { post } from "../requestHelper";
-const entity = 'users'
+import { post } from '../requestHelper';
+const entity = 'users';
 
 export const createUser = async (body) => {
-    return await post(entity, body);
-}
\ No newline at end of file
+  return await post(entity, body);
+};
diff --git a/client/src/services/requestHelper.js b/client/src/services/requestHelper.js
index 43e96de..422f333 100644
--- a/client/src/services/requestHelper.js
+++ b/client/src/services/requestHelper.js
@@ -1,39 +1,39 @@
 const apiUrl = '/api';
 
 export const get = async (entityName, id = '') => {
-    return await makeRequest(`${entityName}/${id}`, 'GET');
-}
+  return await makeRequest(`${entityName}/${id}`, 'GET');
+};
 
 export const post = async (entityName, body) => {
-    return await makeRequest(entityName, 'POST', body);
-}
+  return await makeRequest(entityName, 'POST', body);
+};
 
 export const put = async (entityName, id, body) => {
-    return await makeRequest(`${entityName}/${id}`, 'PUT', body);
-}
+  return await makeRequest(`${entityName}/${id}`, 'PUT', body);
+};
 
 export const deleteReq = async (entityName, id) => {
-    return await makeRequest(`${entityName}/${id}`, 'DELETE');
-}
+  return await makeRequest(`${entityName}/${id}`, 'DELETE');
+};
 
 const makeRequest = async (path, method, body) => {
-    try {
-        const url = `${apiUrl}/${path}`
-        const res = await fetch(url, {
-            method,
-            body: body ? JSON.stringify(body) : undefined ,
-            headers: { "Content-Type": "application/json" }
-        });
-
-        const dataObj = await res.json();
-
-        if(res.ok) {
-            return dataObj;
-        }
-
-        alert(`${dataObj.message}`);
-        return dataObj;
-    } catch (err) {
-        console.error(err);
+  try {
+    const url = `${apiUrl}/${path}`;
+    const res = await fetch(url, {
+      method,
+      body: body ? JSON.stringify(body) : undefined,
+      headers: { 'Content-Type': 'application/json' },
+    });
+
+    const dataObj = await res.json();
+
+    if (res.ok) {
+      return dataObj;
     }
-}
\ No newline at end of file
+
+    alert(`${dataObj.message}`);
+    return dataObj;
+  } catch (err) {
+    console.error(err);
+  }
+};
diff --git a/constants/errorMessages.js b/constants/errorMessages.js
new file mode 100644
index 0000000..d292eea
--- /dev/null
+++ b/constants/errorMessages.js
@@ -0,0 +1,47 @@
+// User
+const invalidData = 'Invalid user data';
+const invalidEmail =
+  'This is not a valid email. You need to register using a gmail email account';
+const invalidPhone =
+  'Telephone number must match the following format: +380xxxxxxxxx';
+const invalidPass = 'Password must be at least 3 characters long';
+const userNotFound = 'User not found';
+const userExists = 'User already exists';
+
+// Fighter
+const invalidFighterData = 'Invalid fighter data';
+const invalidPower = 'Power must be a number from 1 to 100';
+const invalidDefense = 'Defense must be a number from 1 to 10';
+const invalidHealth = 'Health must be a number from 80 to 120 (default - 100)';
+const fighterNotFound = 'Fighter not found';
+const fighterExists = 'A fighter with this name already exists';
+
+// Fight
+const invalidFightData = 'Invalid fight data';
+
+// Exports
+export const errorMessages = {
+  emptyBody: 'Request body is empty',
+
+  user: {
+    invalidData,
+    invalidEmail,
+    invalidPhone,
+    invalidPass,
+    userNotFound,
+    userExists,
+  },
+
+  fighter: {
+    invalidFighterData,
+    invalidPower,
+    invalidDefense,
+    invalidHealth,
+    fighterNotFound,
+    fighterExists,
+  },
+
+  fight: {
+    invalidFightData,
+  },
+};
diff --git a/constants/regex.js b/constants/regex.js
new file mode 100644
index 0000000..3439ea1
--- /dev/null
+++ b/constants/regex.js
@@ -0,0 +1,4 @@
+export const regex = {
+  email: /^[a-zA-Z0-9.!#$%&'*+\/=?^_`{|}~-]+(@gmail.com)$/i,
+  phoneNumber: /^\+?3?8?(0\d{9})$/i,
+};
diff --git a/controllers/authControllers.js b/controllers/authControllers.js
new file mode 100644
index 0000000..566f4b3
--- /dev/null
+++ b/controllers/authControllers.js
@@ -0,0 +1,16 @@
+import { authService } from '../services/authService.js';
+import { decorator } from '../decorators/decorator.js';
+
+// *********************************************************
+
+const login = (req, res) => {
+  const { email, password } = req.body;
+  const data = authService.login({ email, password });
+  res.data = data;
+};
+
+// *********************************************************
+
+export const authCtrl = {
+  login: decorator(login),
+};
diff --git a/controllers/fighterControllers.js b/controllers/fighterControllers.js
new file mode 100644
index 0000000..3622380
--- /dev/null
+++ b/controllers/fighterControllers.js
@@ -0,0 +1,45 @@
+import { decorator } from '../decorators/decorator.js';
+import { fighterService } from '../services/fighterService.js';
+
+// *********************************************************
+
+const getAll = (req, res) => {
+  res.data = fighterService.getAllFighters();
+};
+
+const getCurrent = (req, res) => {
+  const { id } = req.params;
+  res.data = fighterService.search({ id });
+};
+
+const create = (req, res) => {
+  const { health, source } = req.body;
+  if (!health) {
+    req.body.health = 100;
+  }
+  if (!source) {
+    req.body.source = 'https://media.giphy.com/media/kdHa4JvihB2gM/giphy.gif';
+  }
+
+  if (!res.error) res.data = fighterService.createFighter(req.body);
+};
+
+const edit = (req, res) => {
+  const { id } = req.params;
+  const data = req.body;
+  res.data = fighterService.editFighter(id, data);
+};
+
+const remove = (req, res) => {
+  const { id } = req.params;
+  res.data = fighterService.deleteFighter(id);
+};
+// *********************************************************
+
+export const fighterCtrl = {
+  getAll: decorator(getAll),
+  getCurrent: decorator(getCurrent),
+  create: decorator(create),
+  edit: decorator(edit),
+  remove: decorator(remove),
+};
diff --git a/controllers/fightsControllers.js b/controllers/fightsControllers.js
new file mode 100644
index 0000000..2f909cc
--- /dev/null
+++ b/controllers/fightsControllers.js
@@ -0,0 +1,25 @@
+import { decorator } from '../decorators/decorator.js';
+import { fightService } from '../services/fightService.js';
+
+// *********************************************************
+
+const getAll = (req, res) => {
+  res.data = fightService.getAllFights();
+};
+
+const getCurrent = (req, res) => {
+  const { id } = req.params;
+  res.data = fightService.search({ id });
+};
+
+const save = (req, res) => {
+  if (!res.error) res.data = fightService.save(req.body);
+};
+
+// *********************************************************
+
+export const fightsCtrl = {
+  getAll: decorator(getAll),
+  getCurrent: decorator(getCurrent),
+  save: decorator(save),
+};
diff --git a/controllers/userControllers.js b/controllers/userControllers.js
new file mode 100644
index 0000000..8466766
--- /dev/null
+++ b/controllers/userControllers.js
@@ -0,0 +1,38 @@
+import { decorator } from '../decorators/decorator.js';
+import { userService } from '../services/userService.js';
+
+// *********************************************************
+
+const getAll = (req, res) => {
+  res.data = userService.getAllUsers();
+};
+
+const getCurrent = (req, res) => {
+  const { id } = req.params;
+  res.data = userService.search({ id });
+};
+
+const create = (req, res) => {
+  if (!res.error) res.data = userService.register(req.body);
+};
+
+const edit = (req, res) => {
+  const { id } = req.params;
+  const data = req.body;
+  res.data = userService.editUser(id, data);
+};
+
+const remove = (req, res) => {
+  const { id } = req.params;
+  res.data = userService.deleteUser(id);
+};
+
+// *********************************************************
+
+export const userCtrl = {
+  getAll: decorator(getAll),
+  getCurrent: decorator(getCurrent),
+  create: decorator(create),
+  edit: decorator(edit),
+  remove: decorator(remove),
+};
diff --git a/decorators/decorator.js b/decorators/decorator.js
new file mode 100644
index 0000000..6c9c745
--- /dev/null
+++ b/decorators/decorator.js
@@ -0,0 +1,11 @@
+export const decorator = (controllerFunc) => {
+  return (req, res, next) => {
+    try {
+      controllerFunc(req, res);
+    } catch (error) {
+      res.error = error;
+    } finally {
+      next();
+    }
+  };
+};
diff --git a/index.js b/index.js
index 0cfb1e5..fcbe8b3 100644
--- a/index.js
+++ b/index.js
@@ -1,8 +1,8 @@
-import cors from "cors";
-import express from "express";
-import { initRoutes } from "./routes/routes.js";
+import cors from 'cors';
+import express from 'express';
+import { initRoutes } from './routes/routes.js';
 
-import "./config/db.js";
+import './config/db.js';
 
 const app = express();
 
@@ -12,7 +12,7 @@ app.use(express.urlencoded({ extended: true }));
 
 initRoutes(app);
 
-app.use("/", express.static("./client/build"));
+app.use('/', express.static('./client/build'));
 
 const port = 3080;
 app.listen(port, () => {});
diff --git a/middlewares/fight.validation.middleware.js b/middlewares/fight.validation.middleware.js
new file mode 100644
index 0000000..426ef08
--- /dev/null
+++ b/middlewares/fight.validation.middleware.js
@@ -0,0 +1,37 @@
+import { FIGHT } from '../models/fight.js';
+import { errorMessages } from '../constants/errorMessages.js';
+import { fightService } from '../services/fightService.js';
+
+// *********************************************************
+
+const fightKeys = Object.keys(FIGHT);
+const fightSchema = [...fightKeys];
+const indexOfId = fightSchema.indexOf('id');
+fightSchema.splice(indexOfId, 1);
+
+// *********************************************************
+
+// New fight validation
+export const saveFightValid = (req, res, next) => {
+  //
+
+  const bodyKeys = Object.keys(req.body);
+
+  // Body is empty
+  if (!bodyKeys.length) {
+    res.error = errorMessages.emptyBody;
+    next();
+  }
+
+  // Some required fields are missing, or extra fields have been detected
+  const matches = bodyKeys.every((bodyKey) =>
+    fightSchema.find((fighterKey) => fighterKey === bodyKey)
+  );
+
+  if (!matches) {
+    res.error = errorMessages.fight.invalidFightData;
+    next();
+  }
+
+  next();
+};
diff --git a/middlewares/fighter.validation.middleware.js b/middlewares/fighter.validation.middleware.js
index 9945224..13248cb 100644
--- a/middlewares/fighter.validation.middleware.js
+++ b/middlewares/fighter.validation.middleware.js
@@ -1,12 +1,136 @@
-import { FIGHTER } from "../models/fighter.js";
+import { FIGHTER } from '../models/fighter.js';
+import { errorMessages } from '../constants/errorMessages.js';
+import { fighterService } from '../services/fighterService.js';
 
+// *********************************************************
+
+const fighterKeys = Object.keys(FIGHTER);
+const fighterSchema = [...fighterKeys];
+
+const indexOfId = fighterSchema.indexOf('id');
+fighterSchema.splice(indexOfId, 1);
+
+const indexOfHealth = fighterSchema.indexOf('health');
+fighterSchema.splice(indexOfHealth, 1);
+
+// *********************************************************
+
+// New fighter validation
 const createFighterValid = (req, res, next) => {
-  // TODO: Implement validatior for FIGHTER entity during creation
+  //
+
+  const bodyKeys = Object.keys(req.body);
+
+  // Body is empty
+  if (!bodyKeys.length) {
+    res.error = errorMessages.emptyBody;
+    next();
+  }
+
+  // Some required fields are missing, or extra fields have been detected
+  const matches = bodyKeys.every(
+    (bodyKey) =>
+      fighterSchema.find((fighterKey) => fighterKey === bodyKey) ||
+      bodyKey === 'health'
+  );
+
+  if (!matches) {
+    res.error = errorMessages.fighter.invalidFighterData;
+    next();
+  }
+
+  const { name, health, power, defense } = req.body;
+
+  // Fighter name already exists
+  const doesNameExist = fighterService.search({ name });
+
+  if (doesNameExist) {
+    res.error = errorMessages.fighter.fighterExists;
+    next();
+  }
+
+  const isPowerInvalid = Number.isNaN(power) || !(1 <= power <= 100);
+  const isDefenseInvalid = Number.isNaN(defense) || !(1 <= defense <= 10);
+  const isHealthInvalid = Number.isNaN(health) || !(80 <= health <= 120);
+
+  // Invalid power value
+  if (isPowerInvalid) {
+    res.error = errorMessages.fighter.invalidPower;
+    next();
+  }
+
+  // Invalid defense value
+  if (isDefenseInvalid) {
+    res.error = errorMessages.fighter.invalidDefense;
+    next();
+  }
+
+  // Invalid health value
+  if (health && isHealthInvalid) {
+    res.error = errorMessages.fighter.invalidHealth;
+    next();
+  }
+
   next();
 };
 
+// *********************************************************
+
+// Update fighter validation
+
 const updateFighterValid = (req, res, next) => {
-  // TODO: Implement validatior for FIGHTER entity during update
+  const bodyKeys = Object.keys(req.body);
+
+  // Body is empty
+  if (!bodyKeys.length) {
+    res.error = errorMessages.emptyBody;
+    next();
+  }
+
+  // Not any field matches fighter schema
+  const matches = bodyKeys.some(
+    (bodyKey) =>
+      fighterSchema.find((fighterKey) => fighterKey === bodyKey) ||
+      bodyKey === 'health'
+  );
+
+  if (!matches) {
+    res.error = errorMessages.fighter.invalidFighterData;
+    next();
+  }
+
+  const { name, health, power, defense } = req.body;
+
+  // Fighter name already exists
+  const nameExists = fighterService.search({ name });
+
+  if (name && nameExists) {
+    res.error = errorMessages.fighter.fighterExists;
+    next();
+  }
+
+  const isPowerInvalid = Number.isNaN(power) || !(1 <= power <= 100);
+  const isDefenseInvalid = Number.isNaN(defense) || !(1 <= defense <= 10);
+  const isHealthInvalid = Number.isNaN(health) || !(80 <= health <= 120);
+
+  // Invalid power value
+  if (power && isPowerInvalid) {
+    res.error = errorMessages.fighter.invalidPower;
+    next();
+  }
+
+  // Invalid defense value
+  if (defense && isDefenseInvalid) {
+    res.error = errorMessages.fighter.invalidDefense;
+    next();
+  }
+
+  // Invalid health value
+  if (health && isHealthInvalid) {
+    res.error = errorMessages.fighter.invalidHealth;
+    next();
+  }
+
   next();
 };
 
diff --git a/middlewares/response.middleware.js b/middlewares/response.middleware.js
index a74208f..7f1dbad 100644
--- a/middlewares/response.middleware.js
+++ b/middlewares/response.middleware.js
@@ -1,6 +1,22 @@
-const responseMiddleware = (req, res, next) => {
-  // TODO: Implement middleware that returns result of the query
-  next();
-};
+export const responseMiddleware = (req, res) => {
+  const errorObj = { error: true, message: '' };
+
+  if (res.error) {
+    errorObj.message = res.error.toString();
+    const statusCode = errorObj.message.includes('already exists') ? 409 : 400;
+    return res.status(statusCode).json(errorObj);
+  }
+
+  if (!res.data) {
+    const parsedBaseUrl = res.req.baseUrl.split('/');
+    const index = parsedBaseUrl.length - 1;
+    const collection = parsedBaseUrl[index];
 
-export { responseMiddleware };
+    const entity = collection === 'users' ? 'User' : 'Fighter'; // TODO: make more future-proof
+
+    errorObj.message = `${entity} not found`;
+    return res.status(404).json(errorObj);
+  }
+
+  return res.json(res.data); // '200 OK' is returned by default
+};
diff --git a/middlewares/user.validation.middleware.js b/middlewares/user.validation.middleware.js
index f35e98d..bccd0e6 100644
--- a/middlewares/user.validation.middleware.js
+++ b/middlewares/user.validation.middleware.js
@@ -1,13 +1,109 @@
-import { USER } from "../models/user.js";
+import { USER } from '../models/user.js';
+import { userService } from '../services/userService.js';
+import { regex } from '../constants/regex.js';
+import { errorMessages } from '../constants/errorMessages.js';
 
+// *********************************************************
+
+const userKeys = Object.keys(USER);
+const userSchema = [...userKeys];
+
+const indexOfId = userSchema.indexOf('id');
+userSchema.splice(indexOfId, 1);
+
+// *********************************************************
+
+// New user validation
 const createUserValid = (req, res, next) => {
-  // TODO: Implement validatior for USER entity during creation
+  //
+  const bodyKeys = Object.keys(req.body);
+
+  // Body is empty
+  if (!bodyKeys.length) {
+    res.error = errorMessages.emptyBody;
+    next();
+  }
+
+  // Some required fields are missing, or extra fields have been detected
+  const matches = bodyKeys.every((bodyKey) =>
+    userSchema.find((userKey) => userKey === bodyKey)
+  );
+
+  if (!matches) {
+    res.error = errorMessages.user.invalidData;
+    next();
+  }
+
+  const { email, phoneNumber, password } = req.body;
+
+  // Invalid email
+  if (!regex.email.test(email)) {
+    res.error = errorMessages.user.invalidEmail;
+    next();
+  }
+
+  // Invalid phone number
+  if (!regex.phoneNumber.test(phoneNumber)) {
+    res.error = errorMessages.user.invalidPhone;
+    next();
+  }
+
+  // Email or phone number already exists
+  const doesEmailExist = userService.search({ email });
+  const doesPhoneExist = userService.search({ phoneNumber });
+
+  if (doesEmailExist || doesPhoneExist) {
+    res.error = errorMessages.user.userExists;
+    next();
+  }
+
+  if (typeof password !== 'string' || password.length < 3) {
+    res.error = errorMessages.user.invalidPass;
+    next();
+  }
+
   next();
 };
 
+// *********************************************************
+
+// Update user validation
 const updateUserValid = (req, res, next) => {
-  // TODO: Implement validatior for user entity during update
+  const bodyKeys = Object.keys(req.body);
+
+  // Body is empty
+  if (!bodyKeys.length) {
+    res.error = errorMessages.user.emptyBody;
+    next();
+  }
+
+  // Not any field matches user schema
+  const matches = bodyKeys.some((bodyKey) =>
+    userSchema.find((userKey) => userKey === bodyKey)
+  );
+
+  if (!matches) {
+    res.error = errorMessages.user.invalidData;
+    next();
+  }
+
+  const { email, phoneNumber } = req.body;
+
+  // Invalid email
+  if (email && !regex.email.test(email)) {
+    res.error = errorMessages.user.invalidEmail;
+    next();
+  }
+
+  // Invalid phone number
+  if (phoneNumber && !regex.phoneNumber.test(phoneNumber)) {
+    res.error = errorMessages.user.invalidPhone;
+    next();
+  }
+
   next();
 };
 
+// *********************************************************
+
 export { createUserValid, updateUserValid };
diff --git a/models/fight.js b/models/fight.js
index 1489564..93ca97c 100644
--- a/models/fight.js
+++ b/models/fight.js
@@ -1,15 +1,13 @@
-const FIGHT = {
-  id: "",
-  fighter1: "id",
-  fighter2: "id",
+export const FIGHT = {
+  id: '',
+  fighter1: 'id',
+  fighter2: 'id',
   log: [
     // {
-    //     "fighter1Shot": 0,
-    //     "fighter2Shot": 0,
-    //     "fighter1Health": 0,
-    //     "fighter2Health": 0
+    //   "fighter1Shot": 0,
+    //   "fighter2Shot": 0,
+    //   "fighter1Health": 0,
+    //   "fighter2Health": 0
     // }
   ],
 };
-
-export { FIGHT };
diff --git a/models/fighter.js b/models/fighter.js
index 17b7be2..5f2d74b 100644
--- a/models/fighter.js
+++ b/models/fighter.js
@@ -1,9 +1,7 @@
-const FIGHTER = {
-  id: "",
-  name: "",
-  health: 100,
-  power: 0,
+export const FIGHTER = {
+  id: '',
+  name: '', // unique
+  health: 100, // 80 to 120
+  power: 0, // 1 to 100
   defense: 1, // 1 to 10
 };
-
-export { FIGHTER };
diff --git a/models/user.js b/models/user.js
index fa769d8..5ff09bd 100644
--- a/models/user.js
+++ b/models/user.js
@@ -1,10 +1,8 @@
-const USER = {
-  id: "",
-  firstName: "",
-  lastName: "",
-  email: "",
-  phoneNumber: "",
-  password: "", // min 3 symbols
+export const USER = {
+  id: '',
+  firstName: '',
+  lastName: '',
+  email: '', // unique
+  phoneNumber: '', // unique
+  password: '', // min 3 symbols
 };
-
-export { USER };
diff --git a/nodemon.json b/nodemon.json
new file mode 100644
index 0000000..762fa5f
--- /dev/null
+++ b/nodemon.json
@@ -0,0 +1,3 @@
+{
+  "ignore": ["node_modules", "config/database.json"]
+}
diff --git a/package-lock.json b/package-lock.json
index e13b30a..9152d35 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -16,11 +16,20 @@
         "request": "2.88.2",
         "uuid": "9.0.1"
       },
+      "devDependencies": {
+        "nodemon": "^3.0.2"
+      },
       "engines": {
         "node": "16.x.x",
         "npm": "8.x.x"
       }
     },
+    "node_modules/abbrev": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/abbrev/-/abbrev-1.1.1.tgz",
+      "integrity": "sha512-nne9/IiQ/hzIhY6pdDnbBtz7DjPTKrY00P/zvPSm5pOFkl6xuGrGnXn/VtTNNfNtAfZ9/1RtehkszU9qcTii0Q==",
+      "dev": true
+    },
     "node_modules/accepts": {
       "version": "1.3.8",
       "resolved": "https://registry.npmjs.org/accepts/-/accepts-1.3.8.tgz",
@@ -48,6 +57,19 @@
         "url": "https://github.com/sponsors/epoberezkin"
       }
     },
+    "node_modules/anymatch": {
+      "version": "3.1.3",
+      "resolved": "https://registry.npmjs.org/anymatch/-/anymatch-3.1.3.tgz",
+      "integrity": "sha512-KMReFUr0B4t+D+OBkjR3KYqvocp2XaSzO55UcB6mgQMd3KbcE+mWTyvVV7D/zsdEbNnV6acZUutkiHQXvTr1Rw==",
+      "dev": true,
+      "dependencies": {
+        "normalize-path": "^3.0.0",
+        "picomatch": "^2.0.4"
+      },
+      "engines": {
+        "node": ">= 8"
+      }
+    },
     "node_modules/array-flatten": {
       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/array-flatten/-/array-flatten-1.1.1.tgz",
@@ -87,6 +109,12 @@
       "resolved": "https://registry.npmjs.org/aws4/-/aws4-1.11.0.tgz",
       "integrity": "sha512-xh1Rl34h6Fi1DC2WWKfxUTVqRsNnr6LsKz2+hfwDxQJWmrx8+c7ylaqBMcHfl1U1r2dsifOvKX3LQuLNZ+XSvA=="
     },
+    "node_modules/balanced-match": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-1.0.2.tgz",
+      "integrity": "sha512-3oSeUO0TMV67hN1AmbXsK4yaqU7tjiHlbxRDZOpH0KW9+CeX4bRAaX0Anxt0tx2MrpRpWwQaPwIlISEJhYU5Pw==",
+      "dev": true
+    },
     "node_modules/bcrypt-pbkdf": {
       "version": "1.0.2",
       "resolved": "https://registry.npmjs.org/bcrypt-pbkdf/-/bcrypt-pbkdf-1.0.2.tgz",
@@ -95,6 +123,15 @@
         "tweetnacl": "^0.14.3"
       }
     },
+    "node_modules/binary-extensions": {
+      "version": "2.2.0",
+      "resolved": "https://registry.npmjs.org/binary-extensions/-/binary-extensions-2.2.0.tgz",
+      "integrity": "sha512-jDctJ/IVQbZoJykoeHbhXpOlNBqGNcwXJKJog42E5HDPUwQTSdjCHdihjj0DlnheQ7blbT6dHOafNAiS8ooQKA==",
+      "dev": true,
+      "engines": {
+        "node": ">=8"
+      }
+    },
     "node_modules/body-parser": {
       "version": "1.20.1",
       "resolved": "https://registry.npmjs.org/body-parser/-/body-parser-1.20.1.tgz",
@@ -118,6 +155,28 @@
         "npm": "1.2.8000 || >= 1.4.16"
       }
     },
+    "node_modules/brace-expansion": {
+      "version": "1.1.11",
+      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-1.1.11.tgz",
+      "integrity": "sha512-iCuPHDFgrHX7H2vEI/5xpz07zSHB00TpugqhmYtVmMO6518mCuRMoOYFldEBl0g187ufozdaHgWKcYFb61qGiA==",
+      "dev": true,
+      "dependencies": {
+        "balanced-match": "^1.0.0",
+        "concat-map": "0.0.1"
+      }
+    },
+    "node_modules/braces": {
+      "version": "3.0.2",
+      "resolved": "https://registry.npmjs.org/braces/-/braces-3.0.2.tgz",
+      "integrity": "sha512-b8um+L1RzM3WDSzvhm6gIz1yfTbBt6YTlcEKAvsmqCZZFw46z626lVj9j1yEPW33H5H+lBQpZMP1k8l+78Ha0A==",
+      "dev": true,
+      "dependencies": {
+        "fill-range": "^7.0.1"
+      },
+      "engines": {
+        "node": ">=8"
+      }
+    },
     "node_modules/bytes": {
       "version": "3.1.2",
       "resolved": "https://registry.npmjs.org/bytes/-/bytes-3.1.2.tgz",
@@ -143,6 +202,33 @@
       "resolved": "https://registry.npmjs.org/caseless/-/caseless-0.12.0.tgz",
       "integrity": "sha512-4tYFyifaFfGacoiObjJegolkwSU4xQNGbVgUiNYVUxbQ2x2lUsFvY4hVgVzGiIe6WLOPqycWXA40l+PWsxthUw=="
     },
+    "node_modules/chokidar": {
+      "version": "3.5.3",
+      "resolved": "https://registry.npmjs.org/chokidar/-/chokidar-3.5.3.tgz",
+      "integrity": "sha512-Dr3sfKRP6oTcjf2JmUmFJfeVMvXBdegxB0iVQ5eb2V10uFJUCAS8OByZdVAyVb8xXNz3GjjTgj9kLWsZTqE6kw==",
+      "dev": true,
+      "funding": [
+        {
+          "type": "individual",
+          "url": "https://paulmillr.com/funding/"
+        }
+      ],
+      "dependencies": {
+        "anymatch": "~3.1.2",
+        "braces": "~3.0.2",
+        "glob-parent": "~5.1.2",
+        "is-binary-path": "~2.1.0",
+        "is-glob": "~4.0.1",
+        "normalize-path": "~3.0.0",
+        "readdirp": "~3.6.0"
+      },
+      "engines": {
+        "node": ">= 8.10.0"
+      },
+      "optionalDependencies": {
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+      "version": "2.0.5",
+      "resolved": "https://registry.npmjs.org/undefsafe/-/undefsafe-2.0.5.tgz",
+      "integrity": "sha512-WxONCrssBM8TSPRqN5EmsjVrsv4A8X12J4ArBiiayv3DyyG3ZlIg6yysuuSYdZsVz3TKcTg2fd//Ujd4CHV1iA==",
+      "dev": true
+    },
     "unpipe": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/unpipe/-/unpipe-1.0.0.tgz",
@@ -1903,6 +2570,12 @@
           "integrity": "sha512-3lqz5YjWTYnW6dlDa5TLaTCcShfar1e40rmcJVwCBJC6mWlFuj0eCHIElmG1g5kyuJ/GD+8Wn4FFCcz4gJPfaQ=="
         }
       }
+    },
+    "yallist": {
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/yallist/-/yallist-4.0.0.tgz",
+      "integrity": "sha512-3wdGidZyq5PB084XLES5TpOSRA3wjXAlIWMhum2kRcv/41Sn2emQ0dycQW4uZXLejwKvg6EsvbdlVL+FYEct7A==",
+      "dev": true
     }
   }
 }
diff --git a/package.json b/package.json
index cdc6d97..07562d0 100644
--- a/package.json
+++ b/package.json
@@ -8,7 +8,8 @@
     "test": "sh -c 'env REPO_URL=$0 npx mocha tests/**/*.spec.js -R JSON --exit'",
     "test-local": "./node_modules/.bin/mocha tests/**/*.spec.js --exit -R JSON",
     "start": "node index.js",
-    "build-front": "cd client | ls",
+    "start:dev": "nodemon index.js",
+    "build-front": "cd client && npm run build",
     "feedback": "node ./feedback/index.js",
     "generate": "npm run test-local | npm run feedback"
   },
@@ -28,5 +29,8 @@
   "engines": {
     "node": "16.x.x",
     "npm": "8.x.x"
+  },
+  "devDependencies": {
+    "nodemon": "^3.0.2"
   }
 }
diff --git a/repositories/baseRepository.js b/repositories/baseRepository.js
index 93c3766..eedfc96 100644
--- a/repositories/baseRepository.js
+++ b/repositories/baseRepository.js
@@ -1,5 +1,5 @@
-import { dbAdapter } from "../config/db.js";
-import { v4 } from "uuid";
+import { dbAdapter } from '../config/db.js';
+import { v4 } from 'uuid';
 
 class BaseRepository {
   constructor(collectionName) {
diff --git a/repositories/fightRepository.js b/repositories/fightRepository.js
index e268f7c..82c0109 100644
--- a/repositories/fightRepository.js
+++ b/repositories/fightRepository.js
@@ -1,11 +1,9 @@
-import { BaseRepository } from "./baseRepository.js";
+import { BaseRepository } from './baseRepository.js';
 
 class FightRepository extends BaseRepository {
   constructor() {
-    super("fights");
+    super('fights');
   }
 }
 
-const fightRepository = new FightRepository();
-
-export { fightRepository };
+export const fightRepository = new FightRepository();
diff --git a/repositories/userRepository.js b/repositories/userRepository.js
index 8bfc663..b3d9beb 100644
--- a/repositories/userRepository.js
+++ b/repositories/userRepository.js
@@ -1,11 +1,9 @@
-import { BaseRepository } from "./baseRepository.js";
+import { BaseRepository } from './baseRepository.js';
 
 class UserRepository extends BaseRepository {
   constructor() {
-    super("users");
+    super('users');
   }
 }
 
-const userRepository = new UserRepository();
-
-export { userRepository };
+export const userRepository = new UserRepository();
diff --git a/routes/authRoutes.js b/routes/authRoutes.js
index f390a40..d58b814 100644
--- a/routes/authRoutes.js
+++ b/routes/authRoutes.js
@@ -1,22 +1,13 @@
-import { Router } from "express";
-import { authService } from "../services/authService.js";
-import { responseMiddleware } from "../middlewares/response.middleware.js";
+import { Router } from 'express';
+import { responseMiddleware } from '../middlewares/response.middleware.js';
+import { authCtrl } from '../controllers/authControllers.js';
+
+// *********************************************************
 
 const router = Router();
 
-router.post(
-  "/login",
-  (req, res, next) => {
-    try {
-      // TODO: Implement login action (get the user if it exist with entered credentials)
-      res.data = data;
-    } catch (err) {
-      res.err = err;
-    } finally {
-      next();
-    }
-  },
-  responseMiddleware
-);
+// *********************************************************
+
+router.post('/login', authCtrl.login, responseMiddleware);
 
 export { router };
diff --git a/routes/fightRoutes.js b/routes/fightRoutes.js
index de8265f..35ae2f5 100644
--- a/routes/fightRoutes.js
+++ b/routes/fightRoutes.js
@@ -1,13 +1,26 @@
-import { Router } from "express";
-import { fightersService } from "../services/fightService.js";
-import {
-  createUserValid,
-  updateUserValid,
-} from "../middlewares/user.validation.middleware.js";
-import { responseMiddleware } from "../middlewares/response.middleware.js";
+import { Router } from 'express';
+import { fightService } from '../services/fightService.js';
+import { saveFightValid } from '../middlewares/fight.validation.middleware.js';
+import { responseMiddleware } from '../middlewares/response.middleware.js';
+import { fightsCtrl } from '../controllers/fightsControllers.js';
+
+// *********************************************************
 
 const router = Router();
 
+// *********************************************************
+
 // OPTIONAL TODO: Implement route controller for fights
 
+// Get all fights
+router.get('/', fightsCtrl.getAll, responseMiddleware);
+
+// Get one fight by id
+router.get('/:id', fightsCtrl.getCurrent, responseMiddleware);
+
+// Save the fight
+router.post('/', saveFightValid, fightsCtrl.save, responseMiddleware);
+
+// *********************************************************
+
 export { router };
diff --git a/routes/fighterRoutes.js b/routes/fighterRoutes.js
index fba6e53..9dbccdf 100644
--- a/routes/fighterRoutes.js
+++ b/routes/fighterRoutes.js
@@ -1,13 +1,33 @@
-import { Router } from "express";
-import { fighterService } from "../services/fighterService.js";
-import { responseMiddleware } from "../middlewares/response.middleware.js";
+import { Router } from 'express';
+import { fighterCtrl } from '../controllers/fighterControllers.js';
+
 import {
   createFighterValid,
   updateFighterValid,
-} from "../middlewares/fighter.validation.middleware.js";
+} from '../middlewares/fighter.validation.middleware.js';
+import { responseMiddleware } from '../middlewares/response.middleware.js';
+
+// *********************************************************
 
 const router = Router();
 
-// TODO: Implement route controllers for fighter
+// *********************************************************
+
+// Get all users
+router.get('/', fighterCtrl.getAll, responseMiddleware);
+
+// Get current user
+router.get('/:id', fighterCtrl.getCurrent, responseMiddleware);
+
+// Register a new user
+router.post('/', createFighterValid, fighterCtrl.create, responseMiddleware);
+
+// Edit user data
+router.put('/:id', updateFighterValid, fighterCtrl.edit, responseMiddleware);
+
+// Delete an existing user
+router.delete('/:id', fighterCtrl.remove, responseMiddleware);
+
+// *********************************************************
 
 export { router };
diff --git a/routes/routes.js b/routes/routes.js
index b207f15..82147b3 100644
--- a/routes/routes.js
+++ b/routes/routes.js
@@ -1,13 +1,13 @@
-import { router as userRoutes } from "./userRoutes.js";
-import { router as authRoutes } from "./authRoutes.js";
-import { router as fighterRoutes } from "./fighterRoutes.js";
-import { router as fightRoutes } from "./fightRoutes.js";
+import { router as userRoutes } from './userRoutes.js';
+import { router as authRoutes } from './authRoutes.js';
+import { router as fighterRoutes } from './fighterRoutes.js';
+import { router as fightRoutes } from './fightRoutes.js';
 
 const initRoutes = (app) => {
-  app.use("/api/users", userRoutes);
-  app.use("/api/fighters", fighterRoutes);
-  app.use("/api/fights", fightRoutes);
-  app.use("/api/auth", authRoutes);
+  app.use('/api/users', userRoutes);
+  app.use('/api/fighters', fighterRoutes);
+  app.use('/api/fights', fightRoutes);
+  app.use('/api/auth', authRoutes);
 };
 
 export { initRoutes };
diff --git a/routes/userRoutes.js b/routes/userRoutes.js
index f5ee661..5ce782d 100644
--- a/routes/userRoutes.js
+++ b/routes/userRoutes.js
@@ -1,13 +1,32 @@
-import { Router } from "express";
-import { userService } from "../services/userService.js";
+import { Router } from 'express';
+import { userCtrl } from '../controllers/userControllers.js';
 import {
   createUserValid,
   updateUserValid,
-} from "../middlewares/user.validation.middleware.js";
-import { responseMiddleware } from "../middlewares/response.middleware.js";
+} from '../middlewares/user.validation.middleware.js';
+import { responseMiddleware } from '../middlewares/response.middleware.js';
+
+// *********************************************************
 
 const router = Router();
 
-// TODO: Implement route controllers for user
+// *********************************************************
+
+// Get all users
+router.get('/', userCtrl.getAll, responseMiddleware);
+
+// Get current user
+router.get('/:id', userCtrl.getCurrent, responseMiddleware);
+
+// Register a new user
+router.post('/', createUserValid, userCtrl.create, responseMiddleware);
+
+// Edit user data
+router.put('/:id', updateUserValid, userCtrl.edit, responseMiddleware);
+
+// Delete an existing user
+router.delete('/:id', userCtrl.remove, responseMiddleware);
+
+// *********************************************************
 
 export { router };
diff --git a/services/authService.js b/services/authService.js
index f62efb1..211be29 100644
--- a/services/authService.js
+++ b/services/authService.js
@@ -1,15 +1,16 @@
-import { userService } from "./userService.js";
+import { userService } from './userService.js';
+import { errorMessages } from '../constants/errorMessages.js';
+
+// *********************************************************
 
 class AuthService {
   login(userData) {
     const user = userService.search(userData);
     if (!user) {
-      throw Error("User not found");
+      throw Error(errorMessages.userNotFound);
     }
     return user;
   }
 }
 
-const authService = new AuthService();
-
-export { authService };
+export const authService = new AuthService();
diff --git a/services/fightService.js b/services/fightService.js
index f53d6d4..997473b 100644
--- a/services/fightService.js
+++ b/services/fightService.js
@@ -1,9 +1,22 @@
-import { fightRepository } from "../repositories/fightRepository.js";
+import { fightRepository } from '../repositories/fightRepository.js';
 
-class FightersService {
-  // OPTIONAL TODO: Implement methods to work with fights
-}
+// *********************************************************
+
+class FightService {
+  getAllFights() {
+    return fightRepository.getAll();
+  }
 
-const fightersService = new FightersService();
+  // Search fights by one or more parameters
+  search(queryObj) {
+    const item = fightRepository.getOne(queryObj);
+    return item ? item : null;
+  }
+
+  // Create a new fight
+  save(data) {
+    return fightRepository.create(data);
+  }
+}
 
-export { fightersService };
+export const fightService = new FightService();
diff --git a/services/fighterService.js b/services/fighterService.js
index fb219cd..aca59dc 100644
--- a/services/fighterService.js
+++ b/services/fighterService.js
@@ -1,9 +1,36 @@
-import { fighterRepository } from "../repositories/fighterRepository.js";
+import { fighterRepository } from '../repositories/fighterRepository.js';
+
+// *********************************************************
 
 class FighterService {
-  // TODO: Implement methods to work with fighters
-}
+  getAllFighters() {
+    return fighterRepository.getAll();
+  }
+
+  // Search fighters by one or more parameters
+  search(queryObj) {
+    const item = fighterRepository.getOne(queryObj);
+    return item ? item : null;
+  }
+
+  // Create a new fighter
+  createFighter(data) {
+    return fighterRepository.create(data);
+  }
 
-const fighterService = new FighterService();
+  // Edit an existing fighter
+  editFighter(id, dataToUpdate) {
+    return fighterRepository.update(id, dataToUpdate);
+  }
+
+  // Delete an existing fighter
+  deleteFighter(id) {
+    const doesExist = this.search({ id });
+    if (!doesExist) return null;
+
+    const [deletedFighter] = fighterRepository.delete(id);
+    return deletedFighter;
+  }
+}
 
-export { fighterService };
+export const fighterService = new FighterService();
diff --git a/services/userService.js b/services/userService.js
index b80b323..ff8560a 100644
--- a/services/userService.js
+++ b/services/userService.js
@@ -1,17 +1,36 @@
-import { userRepository } from "../repositories/userRepository.js";
+import { userRepository } from '../repositories/userRepository.js';
+
+// *********************************************************
 
 class UserService {
-  // TODO: Implement methods to work with user
-
-  search(search) {
-    const item = userRepository.getOne(search);
-    if (!item) {
-      return null;
-    }
-    return item;
+  getAllUsers() {
+    return userRepository.getAll();
+  }
+
+  // Search users by one or more parameters
+  search(queryObj) {
+    const item = userRepository.getOne(queryObj);
+    return item ? item : null;
+  }
+
+  // Create a new user
+  register(data) {
+    return userRepository.create(data);
   }
-}
 
-const userService = new UserService();
+  // Edit an existing user
+  editUser(id, dataToUpdate) {
+    return userRepository.update(id, dataToUpdate);
+  }
+
+  // Delete an existing user
+  deleteUser(id) {
+    const doesExist = this.search({ id });
+    if (!doesExist) return null;
+
+    const [deletedUser] = userRepository.delete(id);
+    return deletedUser;
+  }
+}
 
-export { userService };
+export const userService = new UserService();
