[mrmister1]

They market themselves as open source but as far as I can tell none of their server side code is available.

And if you want to build an app using the telegram system it's basically using their cloud servers.

Does anyone know what their tech stack is?

[beckler]

Where does it say open source? I see where it says they have an open API and protocol, but nothing about source code.

[darklajid]

https://telegram.org/faq#q-why-not-open-source-everything