Are you still using Django, Rails, or Flask to provide API end points to your front end? If not, what do you use?
But if you just want to get an api up quickly its really hard to beat Flask or even Bottle (not sexy but very simple) and I've never used it but Sinatra is supposed to be great, too. Microframeworks are great.
Oh yeah your OS and libc too have them, the computer itself has them. You don't need the things you don't need to not exists in order to make use of what you need.