# Letro iOS

Letro iOS is a modified version of [Element X iOS](https://github.com/element-hq/element-x-ios),
the next-generation [Matrix](https://matrix.org/) client developed by
[Element](https://element.io/) (Element Creations Ltd. / New Vector
Ltd.). It is distributed by Letro Tech GmbH via Apple's App Store
under the name "Letro".

This repository is published as the corresponding source for the
Letro iOS binary, in compliance with the GNU Affero General Public
License, version 3 (AGPLv3) §6.

## Relationship to upstream

- Upstream project: <https://github.com/element-hq/element-x-ios>
- Upstream baseline used by this fork: see
  [`UPSTREAM_VERSION`](UPSTREAM_VERSION)
- Letro modifications, with dates, serving as the AGPLv3 §5(a)
  modification notice for the work as a whole: see
  [`FORK_DIVERGENCE.md`](FORK_DIVERGENCE.md)

Upstream technical documentation — build instructions, contributor
setup, architecture notes — applies unchanged. See the upstream
[README](https://github.com/element-hq/element-x-ios#readme).

## Status

This repository tracks the production source for the Letro iOS app.
Issues and bug reports specific to the Letro fork should be filed
here; issues that reproduce against upstream Element X iOS belong
upstream.

## Copyright

```
Copyright (c) 2026 Letro Tech GmbH <legal@letro.com>  -- modifications
```

The upstream copyright lines (Element Creations Ltd., New Vector
Ltd., and the other upstream contributors) are preserved verbatim
in the source files and in [`LICENSE`](LICENSE), as required by
AGPLv3. Letro does not claim authorship of upstream code; the parts
modified by Letro are identified in
[`FORK_DIVERGENCE.md`](FORK_DIVERGENCE.md).

## License

This software is dual-licensed by Element Creations Ltd. ("Element"):

1. for free under the GNU Affero General Public License, version 3
   or (at your option) any later version (AGPLv3); or
2. under a paid Element Commercial License agreement between you and
   Element.

Letro distributes this fork under option (1), AGPLv3. The full
licence texts are in [`LICENSE`](LICENSE) and
[`LICENSE-COMMERCIAL`](LICENSE-COMMERCIAL). Letro's own modifications
are likewise licensed under AGPLv3.

## Third-party components

Letro iOS bundles third-party components under their own licences,
including the Matrix Rust SDK (Apache-2.0), MapLibre (BSD-2-Clause),
Compound Design Tokens (AGPLv3), and the further Swift Package Manager
dependencies resolved in `Package.resolved`. A consolidated
attribution list is published at
[`THIRD_PARTY_LICENSES.md`](THIRD_PARTY_LICENSES.md) and mirrored
in-app under Settings → About → Acknowledgements.

## Trademarks

"Matrix" is a trademark of The Matrix.org Foundation C.I.C.

"Element" and "Element X" are trademarks of Element Creations Ltd. /
New Vector Ltd.

"Apple" and "App Store" are trademarks of Apple Inc.

Letro is **not** affiliated with, endorsed by, or sponsored by The
Matrix.org Foundation, Element, or Apple Inc. References to "Matrix",
"Element" and the other names above in this repository's source,
documentation, history and configuration are made solely to identify
the upstream protocol and the upstream project from which Letro is
derived, as permitted by nominative fair use.

## Contact

Legal / licensing questions: <legal@letro.com>
Operating entity / imprint: see <https://www.letro.com/imprint>