Lightning is a Matrix client for Linux, Windows and
macOS. The interface is Qt 6 / QML with C++ for the application layer, and the
official matrix-rust-sdk
does synchronisation, timelines, end-to-end encryption, threads and media.
Lightning implements no Matrix cryptography of its own. It is not Electron,
not a web view, and not a fork of another client.
Linux is the primary target. Lightning is usable day to day but young: it is listed as Beta in the Matrix client directory, so expect rough edges.
- Messaging: replies, edits, reactions, mentions, read receipts, pinned messages, polls, drafts, and forwarding to several rooms at once.
- Threads: real Matrix threads in a side panel, encrypted rooms included.
- Encryption: handled by the SDK. Cross-signing, emoji and QR verification, key backup restore, and messages that decrypt in place when a key arrives.
- Search: a local index on your computer, so encrypted rooms are searchable too; server search where the server can read the room.
- Calls: MatrixRTC group calls with audio, camera and screen sharing that work with Element Call. Not yet tested on macOS.
- Spaces: a single activity-ordered list, or a Spaces rail with nested subspaces, drag-to-reorder and local folders.
- Accounts: password or browser (OAuth 2.0 / OIDC) sign-in, several accounts on different homeservers, and signing your other devices in from this one with a code.
- Media: inline images, video, audio and voice messages; stickers, custom emoji and a GIF picker (GIPHY or KLIPY) that sends only your search term.
- Desktop: eleven themes and a theme editor that checks contrast, eleven languages including Arabic, native notifications (with reply where supported), tray, Ctrl+K switcher and rebindable shortcuts.
- Updates: checks for new releases and installs them where the package format allows, verified against a signed manifest.
The full tour, more screenshots and the known limits are in docs/features.md.
Message keyboard navigation covers compose focus, message selection, independent paging and cursor blinking preferences, with a configuration-file example.
On Linux, Flathub is the easiest route. The Flatpak brings its own Qt, GStreamer and C library, so it also runs on distributions too old for the deb, the rpm and the AppImage.
Every release also ships these on
GitHub Releases,
with a SHA256SUMS file:
| Platform | Packages |
|---|---|
| Linux (x86-64) | AppImage, .deb for Debian 13+ or Ubuntu 26.04+, .rpm for Fedora 44+, .flatpak, .snap |
| NixOS | nix run github:Mizerd/lightning, or the flake with its Home Manager module |
| Windows 10+ (x86-64) | MSI, Setup EXE or portable ZIP, per-user by default. Unsigned, so SmartScreen warns |
| macOS 26+ (Apple Silicon) | ZIP. Not notarized, so the first launch needs Open Anyway. Does not update itself |
docs/install.md has the commands, which distributions each package is known to work on, the NixOS flake, all-users installs on Windows and the macOS first-launch steps.
With the repository's Nix flake on Linux:
git clone https://github.com/Mizerd/lightning.git
cd lightning
nix develop -c cmake -S . -B build-rust -G Ninja -DENABLE_RUST_SDK_BACKEND=ON
nix develop -c cmake --build build-rust
scripts/run-dev.shdocs/building.md covers the mock-backend tree, the tests, build options and how the layers fit together.
Bug reports, testing and focused patches are welcome. Read CONTRIBUTING.md first.
- The public repository is https://github.com/Mizerd/lightning. A change arrives as a pull request there or as a patch emailed to the maintainer.
- A pull request is applied on the maintainer's own repository, which GitHub is synchronised from, and then closed, not merged, even when it ships. The issue tracker is the place to report a bug.
- Chat: #lightning:matrix.smetonis.net. Website: https://www.lightning-matrix.org.
End-to-end encryption is handled entirely by the Rust Matrix SDK. Lightning
collects nothing: no analytics, telemetry or crash reporting. Besides your
homeserver it contacts the release host for an anonymous update check (on by
default, sending only Lightning/<version>) and the GitHub mirror when you
install an update, a GIF provider only while the GIF picker is open, and a
linked site only for a link preview you ask for.
Message content, from encrypted rooms too, is stored unencrypted on disk in your account's store directory, readable only by your user account; full-disk encryption is what protects it at rest. Lightning has not been formally security audited.
- Privacy policy: every network path, what is sent, and how to turn it off
- Application updates: how an update is verified
- Code signing policy: Windows and macOS packages are unsigned today; the Ed25519-signed update manifest is the integrity check on every platform
- Third-party notices: what ships inside a release, and under which licence
- Threat model and the security rules for contributors
Copyright © 2026 Rokas Smetonis. Lightning is free software licensed under the GNU General Public License v3.0 or later — see LICENSE.
Maintainer: Rokas Smetonis — antrasrokas@gmail.com