Most messengers have a server in the middle. It is where your messages live, and it is also the single place where they can be read, subpoenaed, or quietly deleted when the company loses interest.

I wanted to see how far you can get without one. ShutChat is the result: an Android messenger where messages travel directly between devices. No server, no account, no sign-up screen.

This is a write-up of the parts that were interesting to build, and the parts that were genuinely hard.

The whole access model is one code

There is no address book, no user ID, no registration.…