This is the darknet xmpp server - feel free to register yourself an account.
Client recommendations android: conversations linux: gajim ios: chatsecure
captchas for added security
March 2, 2017
for added security, you have to solve a captcha now, when creating an account.some clients might not be able to display the captchas. try a different client then.
encrypt your messages
December 16, 2016
please encrypt your messages via OTR or even better OMEMO, which also supports sending encrypted messages to offline contacts
May 25, 2018
On 01/06/2018 TLSv1.0 and TLSv1.1 are deactivated. Only TLSv1.2 will be supported from that point on. Please check your devices and clients for support and migrate your account to a different server if necessary.