Hi HN, Balboa dev here,
Just as a bit of background of where we're coming from: we've been working on Balboa for the past year or so, after realizing that there wasn't a good end-to-end collaboration product out there that we felt we could use with our clients. In terms of how we're a "Slack alternative", we think Slack is a fantastic product, especially in terms of workflow, so we decided to model our chat interface off their good work. As you'll quickly see, we're not nearly as feature-rich at Slack at this point (nor are we aimed at the same audience). Features that define Slack, like search, are harder to pull off in an end-to-end system, but they're areas of growing research, and we're excited to try our hand there.
Also, we wanted to just give a shout-out to some technologies we've had the pleasure of using:
1) Clojure. Our entire backend is in Clojure, and our frontend, Clojurescript.
2) Zerotier. A great and simple way to get our backend services to talk to one another with end-to-end encryption.
3) Emscripten/Asm.js for transpiled, fast in-app crypto.
4) Skein/Threefish and TweetNaCl.
5) Cassandra and Redis for our data store and key management, respectively.
6) ZeroMQ for communicating between our services.
Thanks to all involved in the projects above who are helping us get to secure collaboration!