Shtuff Chat - Free Group / Team chat with persistent history.
Missive - Team communication app now supporting FB, Twitter & SMS
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Spike - Spike solves businesses' communication chaos by bringing together email, team chat, collaborative docs, and meetings, into one feed.
Kandan - Open Source private chat server. Your own private Chat server in minutes, plus additional features.
Mailtrim - Email lives forever!. Reinvigorate your emailing experience with the best free email client, the Mailtrim