This is a simple server example that accepts geojson features as POST requests (fair warning, it does no validation to make sure anything is geojson conformant) and spits out a geojson file with all the features wrapped in a feature array.
This is just an example. It does lots of bad things (like reading / writing the entire file every time it gets a post request) and is easily abused. The authentication isn't exactly secure either. By default it listens on :2230
.