There are a lot of haters of Telegram on HN and I think one of the reason is that they are a Russian company or the fact that a Russian developer found the flaw

There are a lot of haters of Telegram on HN and I think one of the reason is that they are a Russian company or the fact that a Russian developer found the flaw first. :) But wasn't Pavel Durov the one who offered Edward Snowden a job back then? There are many "secure messaging" apps out there, but they all suck in terms of UX. Telegram looks nice and will only get better. Also, they have an API since day one. Show some respect!