I2PChat | Secure P2P Instant Messenger

End-to-end encrypted peer-to-peer messenger over I2P. Uses the SAM bridge for anonymous, serverless communication with full file transfer support.

Screenshots

screenshot-roster screenshot-chat

Downloads

Latest CI build (all platforms)

Linux (binary)
Windows (.exe)
macOS
Debian/Ubuntu (.deb)
Sounds (.zip)

Features

Peer-to-peer messaging over I2P — no central server, E2E encrypted via garlic routing
Transient (session-only) identity — no keys persisted to disk
Offline message queue — compose while offline, delivered automatically on reconnect
File transfer with per-user auto-download policy
Optional b32.i2p web profile page — drop HTML, CSS, JS, and images into ~/.i2pchat/www/ for a multi-file static site at your b32 address
Multi-user web server with per-user folder mapping, HTTP Basic Auth, cookie sessions, and directory listing
Configurable tunnel length, quantity, and backup; ECIES (Ratchet) and EdDSA
Emoticon support with punctuation-boundary detection

Build instructions

The project includes a build.sh wrapper script that handles compilation, optional AppImage packaging, Windows cross-compilation via MXE, clang-format, clang-tidy, and version bumping.

Prerequisites

Linux distribution package commands

Debian / Ubuntu:
sudo apt-get install build-essential qt5-qmake qtbase5-dev qtmultimedia5-dev libqt5svg5-dev libqt5xml5-dev pkg-config
Fedora / RHEL:
sudo dnf install gcc-c++ qt5-qtbase-devel qt5-qtmultimedia-devel qt5-qtsvg-devel qt5-qtxml-devel make pkgconfig
Arch Linux:
sudo pacman -S base-devel qt5-base qt5-multimedia qt5-svg qt5-xml pkgconf

AppImage (--appimage): needs wget plus the native prerequisites above.
Windows cross-compile (--windows): needs git gperf libtool plus the native prerequisites. MXE is cloned and built automatically on first run.
UPX compression (--upx): needs upx.
.deb package (--deb): needs dpkg-deb (pre-installed on Debian/Ubuntu).
Format (--format): needs clang-format.
Tidy (--tidy): needs clang-tidy bear compiledb.

Usage

bash build.sh [OPTIONS]

Options:
  --clean       Clean previous build artifacts before building
  --format      Run clang-format (auto-fix sources)
  --tidy        Run clang-tidy with --fix (check and auto-fix issues)
  --appimage    Build portable AppImage (Linux only)
  --deb         Build .deb package (Linux only)
  --windows     Cross-compile Windows .exe via MinGW-w64
  --upx         Compress binary with UPX (reduces size, all platforms)
  --bump        Bump patch version, update Core.h and create git tag
  -j N          Use N parallel jobs (default: all cores)
  -h, --help    Show this help

Manual compilation (without build.sh):

qmake I2PChat.pro "CONFIG += release"
make -j$(nproc)

Running

On Linux, bash build.sh creates a stripped binary at dist/I2PChat. Run it with ./dist/I2PChat.

Enable the SAM application bridge in your router: Java I2P+ / I2P via Client Configuration, or i2pd via i2pd.conf's [SAM] section.
Select Online from the dropdown menu. Your unique I2P destination is created automatically on first SAM connection.
Settings and contacts are stored in ~/.i2pchat/ (Linux) or %APPDATA%\Roaming\I2PChat\ (Windows).

Web server

Static files in ~/.i2pchat/www/ (or a custom docroot) are served on your b32.i2p address. Supports HTTP Basic Auth, per-user folder mapping, cookie-based sessions, directory listing, and rate-limited login. Visit Settings → Web Server to configure:

Require login — when ON, all paths challenge for credentials; when OFF, only /login challenges and /logout returns to the public root
Session timeout — configurable cookie lifetime (default 60 min)
Users — per-user username, password, and document root folder
Directory listing — file index when no index.html exists

Content-Security-Policy: default-src 'self'; form-action 'none'; base-uri 'none'; frame-ancestors 'none'. Only GET/HEAD accepted. Request headers limited to 4KB. Symlinks rejected. Session cookies are HttpOnly+SameSite=Lax. 3 failed logins = 1h ban. Transport security by I2P's garlic routing.

Sounds

I2PChat plays notification sounds for online/offline events, incoming messages, and file transfers.

Debian/Ubuntu (`.deb`): Sounds are included and automatically copied to ~/.i2pchat/sounds/ on first run.

Other platforms: Download the sounds archive and extract to the config directory:

Linux: ~/.i2pchat/sounds/
Windows: %APPDATA%\Roaming\I2PChat\sounds\
macOS: ~/Library/Application Support/I2PChat/sounds/

Sound files can be customized by editing application.ini under [Sound][SoundFilePath].

License

Licensed under GPLv3.