GitHub is _mostly_ Ruby -- there's Go, Python, C, and I think some Haskell in production on the website (there used to be some Erlang in there too, but iirc that's gone now). The Visual Studio and Unity extensions are written in C#. The new GitHub Desktop is written entirely in Typescript.
Re:Why We Chose Typescript
by staticassertion on Friday June 30, 2017 @07:46PM
(#14674304)
Yes, exactly. Thanks very much. Do you know if Facebook/ Youtube are still in PHP / Python?
Facebook still uses PHP for a lot of templating/page generation, they use a bunch of stuff on the back not least HHVM which was great because it forced/focused the PHP team in a bunch of areas, php7 is a huge I improvement over 5 on just about every metric.
It's not amazing as a language still but it's much much better and the ecosystem has really improved, modern PHP leveraging good composer components is pretty good.
Even some good static analysis tooling these days.
- Wikipedia is mostly PHP https://github.com/wikimedia/mediawiki
- Wordpress is PHP https://github.com/WordPress/WordPress
- Facebook started in PHP https://www.quora.com/What-programming-languages-are-used-at...
- YouTube started in Python https://www.quora.com/Is-YouTube-still-written-in-Python
- GitHub is Ruby https://github.com/showcases/projects-that-power-github
- Reddit is mostly Python https://www.reddit.com/wiki/faq#wiki_what_is_reddit_written_...