ChatSecure Messenger is a completely free messaging app for iOS devices that supports OTR, OMEMO and XMPP messaging. ChatSecure is designed to be both free and open source, but we do take donations to help support the ongoing development and maintenance of the app. 

Create an account on any server in the world. 

Download and install the app, register an account and connect to any public server in the world. There is no walled garden and ChatSecure will work with any client that supports OTR, OMEMO and XMPP.

Once you're connected, you can start sending and receiving messages to anyone that is on your server.

If you're on the move, ChatSecure supports the standard messaging APIs for SMS, Voice and MMS.