KiTTY (PuTTY 0.85 port)

KiTTY is a feature-rich fork of PuTTY, the free Windows SSH/Telnet client. This branch is a forward-port of the KiTTY features and more onto current PuTTY 0.85 — so you get KiTTY's extras on top of a modern, security-patched PuTTY core (≈1,200 upstream commits newer than KiTTY's original 0.76b base).

⚠️ Beta release (0.85.1.2-beta). The full KiTTY feature set on a modern, security-patched PuTTY 0.85 core — including a post-quantum key-exchange warning and a console CLI key generator (kittygen-cli.exe). Please still read the known issues below.

Screenshots

(click an image to enlarge)

The configuration dialog (start KiTTY with no session):

A terminal session with a clickable, underlined hyperlink:

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⬇️ Download

Grab the latest build from the Releases page →.

Current release — KiTTY 0.85.1.2-beta:

Download	Use it when
Installer — per-user (no admin)	Recommended. Installs for your user only, no UAC prompt (%LOCALAPPDATA%\Programs\KiTTY).
Installer — system-wide	All users, into Program Files (requires admin).
Portable ZIP	No install — run from a folder or USB stick. Includes kitty_portable.exe and all command-line tools. Executables are not UPX-packed (antivirus-friendly).
Portable ZIP (UPX)	Same contents with kitty.exe/kitty_portable.exe UPX-packed for the smallest download. Some antivirus engines dislike UPX — if in doubt, take the standard ZIP.

Both installers add Start-Menu + Desktop shortcuts and an Add/Remove-Programs entry, and uninstall cleanly. Every download is checksummed (SHA256SUMS in the ZIP), and all executables are Authenticode-signed.

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What's included (KiTTY++ features on PuTTY 0.85)

~46 KiTTY features are ported and verified, including:

• Window: transparency, maximize / fullscreen / saved position on start, always-on-top, roll-up, send-to-tray (auto + on-minimize), per-session icons, background image.
• Hyperlinks: clickable URLs in the terminal (Ctrl+click configurable) with underlining.
• Sessions & automation: auto-command after login, auto-password, anti-idle keepalive, port-knocking, duplicate-session, immediate-quit, session export/import, scripting (rutty), and an in-terminal command console (Ctrl+F8, type /help; see docs/COMMANDS.md).
• Proxies & jump hosts: reusable named proxy definitions (including SSH jump hosts), selectable per session.
• Security: saved passwords encrypted at rest — Windows DPAPI in registry mode, an opt-in master password for the portable store (travels between machines); a post-quantum key-exchange warning; a built-in update checker that verifies the download's Authenticode signature chain.
• SSH agent (kageant): per-key or global use-confirmation, key-use notifications, a remembered startup-key list, a Windows-OpenSSH-agent bridge, kitty.ini configuration and registry-free autostart for portable installs.
• Transfers / backends: ZModem send/receive, WinSCP & kscp file transfer with directory-aware uploads (OSC 7 — see the callout below), adb (Android) backend.
• Terminal: font resize, protect, print, negative/B&W colours, clear/restart log, far2l extensions.
• Storage: registry or portable file/dir storage (kitty_portable.exe), kitty.ini configuration.
• Plus the standard PuTTY tools, renamed KiTTY-style: klink, kscp, ksftp, kageant, kittygen.
• kittygen-cli.exe — a console-mode CLI key generator (generate, convert, fingerprint) for use in scripts and pipelines. Run kittygen-cli --help for options.
• Quick-Connect or Last-Session Mode: set "loadlastsession=yes/no" and either get fast load the last session or your cursor set to the hostname to enter for a quick connection.
• Double the Folder-Navigation whatever drives you: the mouse or the keyboard the "foldernavigation=yes/no" got you covered set it to yes and you can simply click through your folders in the Session-List; set it no and Ctrl+F and Ctrl+G help you to locate the sessions you need for your next adventure.
• Modal Box Free Work if you don't want Message Boxes popping up if things go sideways, this KiTTY can put those notices in the terminalwindow. Switch to "modalerrors=no" and a message for another terminal can't block your work anymore. More modal-settings are in the kitty.ini and highly recommended if you hate Message Boxes.
• Workplace Proxy Mode working on the go you sometimes have to set a proxy for all your needs. If you have named proxies configured you can simply activate one on the go using the launcher or by starting the workplace-proxy in the KiTTY-config-window (Connection - Proxy) and you are set.

📂 Put your files where your cwd is. Turn on OSC 7 directory tracking and drag-and-drop uploads — and Start WinSCP — land in your shell's current remote directory instead of always dropping into $HOME. It's the safe, data-only rework of KiTTY's old "send file to the current directory" trick, which was retired after that mechanism turned out to be a remote-code-execution hole (CVE-2024-23749): the new one only ever reads a strictly-validated path and never runs anything the remote sends. Two lines in your shell startup do it — OSC 7 how-to →.

Most KiTTY extras read from a kitty.ini ([KiTTY] section). The release includes an inert kitty.ini.example with every supported key commented out; copy/rename it to kitty.ini only when you want an active config file. For example, URL hyperlinks are enabled with:

[KiTTY]
hyperlink=yes

docs/KITTY-INI.md explains the settings file — how KiTTY finds it, the savemode/portable rules, and all its sections — and links the fully annotated kitty.ini.example. See FEATURES.md for the full feature reference, including how to enable each one, and CHANGELOG.md for what changed in each release. Using SSH certificates instead of per-server authorized_keys entries? docs/SSH-CERTIFICATES.md covers the KiTTY side and the OpenSSH server side end to end.

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Known issues

This is a beta: most KiTTY features are restored and verified, but a few have limitations or still want real-world testing. The full, per-release list is in KNOWN-ISSUES.md — current highlights:

• Antivirus / SmartScreen & UPX — the standard ZIP ships only plain, uncompressed signed executables. The -upx.zip flavour and the installers carry UPX-packed kitty.exe/kitty_portable.exe (smallest download), which can trip heuristic AV — if flagged, use the standard ZIP.
• far2l shared clipboard, non-text formats — both directions are verified over the wire (a remote writing your clipboard and reading it, including an 80 KB payload). What is untested is whether non-text formats such as images survive the round trip; only text has been exercised.
• far2l clipboard "Ask" mode (Window → Selection) — answering OK grants the remote clipboard access for the rest of the session (no per-request reprompt). Choose Deny instead if a remote far2l should never reach your clipboard.
• adb backend — verified against test fixtures, not yet against a real Android device.
• Stored passwords — saving passwords is optional; saved ones are encrypted at rest: Windows DPAPI in registry mode (bound to your account/machine), an opt-in master password in portable mode (travels between machines; it is never stored — if you forget it, the passwords it protected are unrecoverable). Neither defends against malware already running as your user; for the strongest security prefer SSH keys (kageant).
• Command-line tools use the registry session store — klink/kscp/ksftp do not read a portable (savemode=dir) store, so portable sessions and their master-password-protected passwords are usable from the GUI only.
• Background image — the thin margin outside the terminal cell grid is still solid-filled (cosmetic).

Found something else? Please open an issue.

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Building from source

Cross-compiled to Win64 with MinGW + CMake (Ninja) under WSL/Linux:

cmake -B build-mingw -G Ninja -DCMAKE_TOOLCHAIN_FILE=cmake/toolchain-mingw.cmake
cmake --build build-mingw                 # whole tree
cmake --build build-mingw --target kitty  # just kitty.exe

The MSI installers are built from windows/installer/ with WiX v5. For an orientation on how this fork is structured and ported — architecture, the MOD_* / parallel-target approach, and the constraints to know before editing shared files — see PORTING.md.

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Credits & licence

• PuTTY © Simon Tatham and the PuTTY team — the upstream this is built on (putty homepage).
• KiTTY © Cyril Dupont (9bis) — the feature fork this port carries forward (https://www.9bis.net/kitty/).
• far2l terminal extensions (the far2l shared clipboard) — derived from the putty4far2l project: far2l's PuTTY extensions originally by Ivan Sorokin, putty4far2l by unxed, the 0.78.5 port by Ivan Shatsky; the far2l file manager by elfmz and contributors.
• RuTTY © 2013-2014 Ernst Dijk — the scripting patch behind Session → Scripting (kitty/rutty/).
• This port keeps PuTTY's MIT licence — see LICENCE.

The original PuTTY source README is preserved as README.