Code Runner is a simple Sinatra app that runs scripts (currently supports Ruby and Python) and returns the output (stdout, stderr, as well as status code) in JSON format.
To run the server,
rackup -p 3000
To run code, simply make a POST request to the root URL, with the parameter code being the file that you want to run. For example,
curl "localhost:3000" -F "code=@/somewhere/hello_world.py"
would give
{"stdout":"Hello, world! \n","stderr":"","status":0,"success":true}