Let's Chat is a persistent, self-hosted messaging application made for small teams. It runs on Node.js and MongoDB and comes with some awesome features, such as LDAP/Kerberos authentication, a REST-like API and XMPP support. It's also got multiple, private and password-protected rooms, mentions, image embeds, and plenty of other great stuff. Let's Chat is Hubot-friendly and comes in many different languages. It's made with love by the development team at Security Compass, who started this project in order to have their very own chat service that had everything they were looking for.