Telegram has various issues for the privacy concerned, namely that group chats are never E2EE and 1-to-1 chats are not encrypted by default, among other concerns[1].

Also Telegram is not open-source.

Also Telegram did some shenanigans with cryptocurrency a few years back[2].

Telegram does have better UX than Signal though.

[1] https://en.wikipedia.org/wiki/Telegram_(software)#Security

[2] https://en.wikipedia.org/wiki/Telegram_(software)#Telegram_O...

> Telegram is not open-source

The Telegram apps are GPL. Their server is (afaik) closed-source, but having an open source server implementation doesn't mean much for a centralised service without any server-switching support anyway, so no effective practical difference to Signal here in that regard.

The E2E situation on Telegram is poor however.

I think the two things (open source servers and E2EE) dovetail together.

If the E2EE situation is poor, what is happening on the backend with your data becomes more relevant.

About twice as many people express a preference for Signal as Telegram here:

https://news.ycombinator.com/item?id=25669864

Uses Approval voting. That poll doesn't show a negative preference (as in: what do you really not want to run).

I'd guess Telegram gets more negative votes than Signal, because of the e2ee+infrastructure trust issue.

The fact that law enforcement seems to have no issue getting Telegram messages is my guess.