aTalk

aTalk is an XMPP client for Android. It connects to accounts on XMPP servers, whether that is a large public service or a server someone runs themselves, and can hold several accounts at once with their rosters kept separate. Day-to-day use is contact-list driven: pick a contact, exchange text messages, send files and media, and see presence and typing state where the other side publishes it. Where the server offers shared rooms, group conversations work through the same interface.

Message encryption is end-to-end and negotiated between the clients rather than terminated at the server, so contents are not readable by the operator of the machine relaying them. The same account also carries voice and video calls, which set up a direct media session between the two devices once the signalling has passed through the server.

Because aTalk is only a client, it does not come with a service attached. An account on some XMPP server is a prerequisite, and which features actually work in practice depends on what that server and the contact's own client support: rooms, file relaying and call setup can all be limited from the server side. The application is packaged for Android; there is no desktop counterpart in this listing.