{[Did you know}} Which programming language is used for these famous websites?

Question

Youtube - Javascript, c, c++, java, python, Go
Google - Javascript, c, c++, java, python, Go
Facebook - Javascript, c++, java, python, Hack, PHP, Erlang, D, Xhp, Haskell
Twitter - Javascript, c++, java, Scala, Ruby on Rails
Amazon - Javascript, c++, java
Yahoo - Javascript, PHP
Add if you know other.

Answer 1

Hey Ram thank you very much for your upvotes. ☺
Now, to the point:
Facebook: php and later they change into their php modification for Facebook only.
Skype is written in Delphi and C++.
PayPal - c++ -> java -> node JS. Complexity of languages and frameworks.
WordPress - php.
Gmail - Java back-end.
GitHub is developed in Ruby programming language.
Twitter - founded on Ruby on rails. Later they replaced ruby.
eBay was originally written in Perl. Later as the site grew up was used C++ back end and XSL for front-end.
Then it was rewritten on Java + XSL in couple versions (Perl, c++》

Answer 2

Microsoft - JavaScript , ASP.NET
Wikipedia - JavaScript, PHP, hack

Answer 3

For the people interested in hack:
Hack is a programming language for HHVM developed by facebook.
Hack reconciles the fast development cycle of a dynamically typed language with the discipline provided by static typing, while adding many features commonly found in other modern programming languages.
Hack provides instantaneous type checking by incrementally checking your files as you edit them. It typically runs in less than 200 milliseconds, making it easy to integrate into your development workflow without introducing a noticeable delay.
Source: hacklang.org

Answer 4

Instagram - python