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.
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 GitLab
and the GitHub mirror,
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://gitlab.smetonis.net/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 canonical repository is https://gitlab.smetonis.net/Mizerd/lightning. Registration there is closed, so a change arrives as a pull request on the GitHub mirror or as a patch emailed to the maintainer.
- github.com/Mizerd/lightning is a read-only mirror. A pull request there is applied on GitLab and then closed, not merged, even when it ships. Its issue tracker is the place to report a bug without an account.
- 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