Open Source Web-Based Chat App: Cryptocat

Cryptocat is an open source and web-based chat application that focuses on making sure that the communication is encrypted and private.

It is built with PHP and works with a single file besides the static files (CSS, JS and images) used.

The interface is simple-yet-nice and messages are encrypted with AES-256 using crypto.js library.

cryptocat is developed by Nadim Kobeissi. It uses the open source crypto-js andseedrandom libraries, and the Bitcons iconset.

For a private group communication inside a chat room with other users, a passkey (used by all of the group) comes to the rescue.

Also, for paranoid users, there is Cryptocat Verifier, a Chrome extension which verifies that your Cryptocat session is not serving you modified JavaScript code.

Requirements: PHP
Compatibility: All Major Browsers
Website: https://crypto.cat/
Download: https://github.com/kaepora/cryptocat