gajim

Gajim aims to be an easy to use and fully-featured XMPP client. It is open source and released under the GNU General Public License (GPL).

FEATURES:

Never miss a message, keep all your chat clients synchronized

Invite friends to group chats or join one

Simply send pictures, videos or other files to friends and groups

Chat securely with End-to-End encryption via OMEMO or PGP.

Use your favorite emoticons, set your own avatar

Keep and manage all your chat history

Organize your chats with tabs

Automatic spell-checking for your messages

Connect to other Messengers via Transports (Facebook, IRC, ...)

Lookup things on Wikipedia, dictionaries or other search engines directly from the chat window

What are you doing just now? Which music are you listing to this moment? How are you feeling lately? If you like, show your friends by setting your activity, tune, and mood

Even more features via plugins, for example: Image Previews, Location Previews, Anti Spam, ...

ADVANCED FEATURES:

Support for multiple accounts

One of your friends has accounts everywhere but you just want one contact you can easily write to? Group multiple contacts to one Meta-Contact

XML console to see what's happening on the protocol layer

Serverless messaging (Bonjour/Zeroconf), BOSH

Support for Service discovery including nodes and search for users