Signal

Details

The project is provided under an AGPLv3 license. This is the license used for all their client sources.

The application talks to a server, which is also provided under an AGPLv3 license. While the server component does appear to be self-hostable, little guidance & support is specifically provided for this use-case, with the project only advising assistance via their unofficial community forum.

While alternative clients and servers can be used, Signal is not designed to be federated, and the founder has indicated that they’d prefer forked application versions not use their naming or server resources.

The project is supported by the Signal Foundation, which received $50m in funding by one of the foundation founders. Signal has also received $3m in funding from the Open Technology Fund, which itself is primarily funded by the US government. The foundation and project also appear to gain funding from donations.