The XMPP service uuxo.net works well with Movim. It supports modern features like OMEMO encryption, group chats (MUC), file uploads, and message syncing. You can register an account directly from Movim using in-band registration.

The service runs on a clustered setup with servers located in Falkenstein, Nuremberg, and Helsinki, offering good performance and reliability, especially in Europe. It’s fully federated, so you can chat with users on other XMPP servers.

File uploads are handled by a custom tool called hmac-file-server, developed by the admin. You can find the project here: https://git.uuxo.net/uuxo/hmac-file-server

Just create an account like username@uuxo.net in Movim, and you're ready to go.