Source is at https://github.com/simplex-chat/simplex-chat under AGPL-3.0 Though currently it does not build on sid due to compiler version mismatch being tracked at https://github.com/simplex-chat/simplex-chat/issues/415 SimpleX - the first messaging platform operating without user identifiers of any kind - 100% private by design! They have a CLI version and their prebuilt binaries are amd64 only.