⏱ TimeShift — Instant Timezone Converter

Convert any time on any webpage in one right-click. No new tab. No searching. Just the answer.

Built by Sheikh Abir Ali — Full-Stack Developer & Open Source Builder

🌐 Live on Chrome	🦊 Live on Firefox	👤 Portfolio

🤔 The Problem

Every remote worker does this multiple times a day:

Sees "10:00 AM EST" in an email
  → Opens a new tab
  → Searches "EST to BDT converter"
  → Types the time manually
  → Gets the answer
  → Closes the tab

That's 6 steps for something that should take 1 second.

✅ The Solution

Select "10:00 AM EST"  →  Right-click  →  "Convert Time with TimeShift"  →  Done.

TimeShift shows the result instantly, right where you are — with the exact converted time, timezone, and date. No new tab. No copy-pasting. No friction.

✨ Features

Feature	Details
⚡ One right-click	Select any time on any webpage → right-click → instant result
🌍 285+ cities	Full IANA timezone database covering every major city worldwide
📅 Exact date shown	Shows `22 Feb 2026 — Sunday`, not just "next day"
🔒 100% offline & private	Zero network calls. Everything runs locally. Nothing ever leaves your device
🖱️ Works everywhere	Gmail, Slack, news articles, any webpage in Chrome or Firefox
📋 Copy in 1 click	Copy the result directly to clipboard
💾 Remembers preferences	Saves your timezone settings between sessions
🔄 Manual converter	Popup with full manual conversion interface
🆓 Free forever	No account, no subscription, no ads

🚀 Install

Chrome

Firefox

🎬 How It Works

Step 1 — Select any time on any webpage

Highlight a time you see anywhere — an email, a Slack message, a news article, a calendar invite.

Step 2 — Right-click it

Click "⏱ Convert Time with TimeShift" from the context menu.

Step 3 — See the result instantly

A floating panel appears right where you are showing the full conversion:

10:00 AM  →  9:00 PM
EST            BDT
New York       Dhaka

📅 22 Feb 2026 — Sunday

No new tab. No searching. You never leave the page.

🗂️ Repository Structure

timeshift/
│
├── chrome/                     # Chrome extension (Manifest V3)
│   ├── manifest.json           # MV3 manifest with service worker
│   ├── background.js           # Service worker — context menu + injection
│   ├── content.js              # Injected overlay UI
│   ├── content.css             # Overlay styles
│   ├── popup.html              # Extension popup interface
│   ├── popup.js                # Popup logic + manual converter
│   ├── timezones.js            # 285+ city timezone database
│   ├── privacy-policy.html     # Privacy policy
│   └── icons/                  # Extension icons (16, 32, 48, 128px)
│
├── firefox/                    # Firefox extension (Manifest V2)
│   ├── manifest.json           # MV2 manifest with Gecko + Android settings
│   ├── background.js           # Background script — tabs.executeScript
│   ├── content.js              # Content script with browser API compat shim
│   ├── content.css             # Overlay styles
│   ├── popup.html              # Extension popup interface
│   ├── popup.js                # Popup logic with browser API compat shim
│   ├── timezones.js            # 285+ city timezone database
│   ├── privacy-policy.html     # Privacy policy
│   └── icons/                  # Extension icons (16, 32, 48, 128px)
│
├── .github/
│   ├── ISSUE_TEMPLATE/
│   │   ├── bug_report.md
│   │   └── feature_request.md
│   └── PULL_REQUEST_TEMPLATE.md
│
├── README.md
├── CONTRIBUTING.md
├── CHANGELOG.md
└── LICENSE

🔧 Run Locally / Development

Chrome

# 1. Clone the repo
git clone https://github.com/bhittu21/timeshift-timezone-converter.git
cd timeshift

# 2. Open Chrome and go to
chrome://extensions/

# 3. Enable "Developer mode" (top-right toggle)

# 4. Click "Load unpacked"

# 5. Select the /chrome folder

Firefox

# 1. Open Firefox and go to
about:debugging#/runtime/this-firefox

# 2. Click "Load Temporary Add-on"

# 3. Navigate to the /firefox folder and select manifest.json

# For permanent install, use the signed version from Firefox Add-ons.

⚙️ Technical Architecture

Chrome (Manifest V3)

Service Worker (background.js) — registers the context menu and handles chrome.scripting.executeScript() for on-demand injection
Content Script (content.js) — injected only when the user triggers the right-click. Idempotent, guarded by window.__timeshiftLoaded
Popup (popup.html + popup.js) — standalone manual conversion interface with timezone search
Storage — chrome.storage.sync for cross-device preference persistence
Zero host permissions — activeTab only, no content_scripts block

Firefox (Manifest V2)

Minimum version — Firefox 140.0 desktop, Firefox for Android 142.0
Background Script — uses browser.tabs.executeScript() (no Scripting API in MV2)
Compat shim in background.js — const api = typeof browser !== 'undefined' ? browser : chrome
Compat shim in content.js and popup.js — const tsApi = typeof browser !== 'undefined' ? browser : chrome
data_collection_permissions — { "required": ["none"] } inside gecko — collects nothing

Timezone Engine

Custom convertTime() using Intl.DateTimeFormat offset calculation — handles DST automatically
Supports 10:30 AM, 10:30, 22:30 and plain 10 input formats
Auto-detects timezone abbreviations in selected text (e.g. EST, BDT, PST)
Day shift detection (+1 / 0 / -1) with exact destination date shown

Privacy Architecture

User selects text
      ↓
background.js (local)
      ↓
content.js injected into current tab
      ↓
Intl.DateTimeFormat() [browser built-in]
      ↓
Result shown in DOM overlay
      ↓
[NOTHING sent anywhere. Ever.]

🔒 Privacy

TimeShift is completely offline. Every conversion happens locally in your browser using JavaScript's built-in Intl API.

❌ No servers
❌ No API calls
❌ No analytics or telemetry
❌ No tracking pixels
❌ No account required
❌ No data stored outside your browser
✅ All data stays 100% on your device

📋 Permissions Explained

Chrome

Permission	Why
`contextMenus`	To add the right-click menu item
`storage`	To remember your timezone preferences
`activeTab`	To inject the overlay into the current tab only
`scripting`	To execute content.js on demand (MV3 requirement)

Firefox

Permission	Why
`contextMenus`	Right-click menu item
`storage`	Save timezone preferences
`activeTab`	Inject into current tab
`tabs`	Required for `tabs.executeScript` in MV2
`<all_urls>`	Required for `tabs.executeScript` in Firefox MV2

No permission reads your browsing history, accesses other tabs, or sends any data.

🗺️ Roadmap

DST warning when conversion crosses a DST boundary
Multi-timezone display (show 3+ cities at once)
World clock popup view
Keyboard shortcut trigger
Calendar app integration (Google Calendar, Outlook)
Time zone group presets (e.g. "My Team")
Dark / light theme toggle
Safari extension port

Have an idea? Open a Feature Request →

🤝 Contributing

Contributions are welcome! Whether it's a bug fix, a new timezone, a UI improvement, or a new feature — please read CONTRIBUTING.md first.

git checkout -b feature/my-improvement
git commit -m "feat: add DST warning on conversion"
git push origin feature/my-improvement
# Then open a Pull Request on GitHub

⚠️ By contributing, you agree that your contributions will be licensed under the same BUSL 1.1 license as this project. Commercial use of any contribution requires written permission from the author.

📦 Changelog

See CHANGELOG.md for the full version history.

v1.0.1 — Current

Firefox version published on Mozilla Add-ons
Firefox for Android supported (gecko_android min version 142.0)
data_collection_permissions: { "required": ["none"] } declared in gecko settings
Browser API compat shim (api / tsApi) across all scripts
Removed broad host permissions warning on Chrome
Fixed date display format (DD Mon YYYY — DayName)
License updated to BUSL 1.1

v1.0.0 — Initial Release

Right-click conversion on any webpage
285+ cities timezone database
Manual popup converter
Copy to clipboard

📄 License

This project is licensed under the Business Source License 1.1 (BUSL 1.1).

In plain English:

✅ You can view, fork, and contribute to the source code
✅ You can use it for personal and non-commercial projects
✅ You can learn from it and build upon it privately
❌ You cannot copy, rebrand, or sell this as your own product
❌ You cannot use it in a commercial product or service without written permission
📩 For commercial licensing, contact: sheikhabirali@gmail.com

See the full LICENSE file for legal terms.

👨‍💻 Author

Sheikh Abir Ali Full-Stack Developer · Open Source Builder

⭐ Support the Project

If TimeShift saves you time, consider:

⭐ Starring this repo — it helps others find it
🧩 Leaving a review on Chrome Web Store or Firefox Add-ons
🐛 Reporting bugs via GitHub Issues
💡 Suggesting features you'd find useful
📢 Sharing it with your remote team

Made with ☕ and frustration at timezone converters · by Sheikh Abir Ali

Name		Name	Last commit message	Last commit date
Latest commit History 9 Commits
.github		.github
timeshift		timeshift
.gitignore		.gitignore
CHANGELOG.md		CHANGELOG.md
CONTRIBUTING.md		CONTRIBUTING.md
LICENSE		LICENSE
README.md		README.md

Folders and files

Latest commit

History

Repository files navigation

⏱ TimeShift — Instant Timezone Converter

🤔 The Problem

✅ The Solution

✨ Features

🚀 Install

Chrome

Firefox

🎬 How It Works

Step 1 — Select any time on any webpage

Step 2 — Right-click it

Step 3 — See the result instantly

🗂️ Repository Structure

🔧 Run Locally / Development

Chrome

Firefox

⚙️ Technical Architecture

Chrome (Manifest V3)

Firefox (Manifest V2)

Timezone Engine

Privacy Architecture

🔒 Privacy

📋 Permissions Explained

Chrome

Firefox

🗺️ Roadmap

🤝 Contributing

📦 Changelog

📄 License

👨‍💻 Author

⭐ Support the Project

About

Topics

Resources

License

Contributing

Uh oh!

Stars

Watchers

Forks

Releases 1

Packages 0

Uh oh!

Contributors

Uh oh!

Languages

Packages