There's a lot of FUD in this comments section, so I'd like to clear the air. I'm pretty big on OSS myself, so it pains me to see a company doing all the right things get lambasted like this.
Beeper is just a Matrix server running in tandem with a series of custom, open source bridges written by Beeper. The value proposition is not having to deploy a Matrix server yourself, and not having to deploy each bridge yourself.
However, if you want to do that you absolutely can. I've been running Synapse + a subset of their bridges for a couple years now (the WhatsApp one being the oldest), and they are fantastic.
The devs contribute back to Matrix all the time and are great about supporting the spec as a responsible third party.
Their only closed source software is their client, which is - by definition - only written to work with their servers and not generic Matrix servers (e.g. It's just a preconfigured matrix client which expects each bridge to be deployed, and doesn't ask you for things like what server you want). As a result, you wouldn't want to use it with your own stack; you can just pick one of the myriad OSS clients available for Matrix and go with that. I use SchildiChat, for example.
I don't understand why, after doing all this work and publishing the source online for free (free as in freedom), they aren't allowed to offer a preconfigured service to non tech savvy folk?
Honest question: Shouldn't they be paid for their work?
Edit: And, please, stop asking questions like "How do they connect to X/Y/Z, anyway?" - just go read the source and see for yourself. These are the good guys working completely in the open, and you're treating them as if Twitter just wrote a chat app.
Turkish middle school, high school, and university exams are very serious.
Basically everyone takes the same set of long exams (with a few additions you can add to your standard exam sets, for specialized schools) and when the results come out, you are compared to all other students in the nation.
Like, think global leaderboards.
The best universities will outright reject you if your ranking isn't high enough.
It's very intense and cut-throat; so much so that - when I was a young'un growing up in Turkey - I just opted to try my hand at the SATs instead. Ended up going to school abroad.
The SATs were so easy, compared to the exam prep we did in our Turkish classes, it almost felt like a joke. Though, college tuition costs definitely made sure I wasn't the one with the last laugh.