A simple (even lacking) web server for debugging clients (yes, really).

debug-server.py

import json
from werkzeug.wrappers import Request, Response


@Request.application
def application(request):
    print('HEADERS:')
    for header, value in request.headers.items():
        print('{header}: {value}'.format(header=header, value=value))
    print('CONTENT:')
    print(json.dumps(request.values.to_dict()))
    print('_'*80)
    return Response('')


if __name__ == '__main__':
    from werkzeug.serving import run_simple
    run_simple('localhost', 4000, application)