Signal Server

Signal-Server is the backend that supports the Signal Private Messenger applications on Android, Desktop and iOS. It is the server counterpart to the open-source Signal clients and is published so the way the service works can be inspected.

The project is written in Java and uses FoundationDB, so building it requires the FoundationDB client library to be installed on the host. Protocol documentation lives on signal.org/docs, and security issues are reported privately by email to the Signal security address. The maintainers say they cannot provide direct technical support, but an unofficial community forum helps people run the software in their own environment.

The code is licensed under the GNU AGPLv3 and carries a cryptography notice reminding users to check their country's rules on encryption software, along with the export classification. It is mainly of interest to developers, researchers and anyone who wants to review or experiment with the server behind Signal.