Langis, is an unofficial, modified version of the Signal application designed specifically to address limitations and privacy concerns related to Google services.

Here are the primary features and functionalities of Langis:

Core Functionality: Google Play Services Removal

• Opting Out of Google Services: Langis is a patched version of Signal that removes support for Google Play Services (specifically used by vanilla Signal to notify devices when new messages arrive).

• Enabling Use on Restricted Devices: The removal of Google Play Services allows Signal to function on any Android device that lacks or has disabled these services. This resolves "corner cases" where the regular version of Signal is unusable, such as on devices running LineageOS with MicroG.

• Privacy Focus: The project aims to give users the choice to opt out of Google Play Services, addressing potential privacy threats associated with their use.

Technical Features and Software Integrity

• Source Code Transparency: Langis is Free Software. The developers follow specific, documented steps to build the application, including providing the source code and build instructions.

• Patching Process: The process involves downloading the source code of the official Signal-Android app, applying a patch to remove Google Play services, and then building the patched version using Signal-Android's reproducible-builds stack.

• Signed APKs: The resulting APKs are signed, which allows users to upgrade their modified Signal application without needing to uninstall the previous version.

• Artifact Archive: All necessary elements for building, including the patch, build steps, and resulting signed APKs for the latest successful build, are available in a published artifacts archive.

Distribution and Installation

• Fdroid Repository: Langis is available through Fdroid via a custom repository called "patched-apps".

• Direct Download: The latest APK is also available via a direct download link.

Known Development Constraint

• Building Difficulty: The developers currently face difficulties building new versions because the Signal (on which Langis is based) now requires more than 16GB of RAM.