Smallest possible Python web server

server.py

# This server returns an empty JSON object, no matter what.

from wsgiref.simple_server import make_server
import threading

def start_server():
    def app(environ, start_response):
        start_response('200 OK', [('Content-Type', 'application/json')])
        return [b'{}']
    
    with make_server('', 8000, app) as httpd:
        httpd.serve_forever()


# Option 1: just run. Control C to stop.
start_server()

# Option 2: start in a background thread (will exit with main thread).
threading.Thread(target=start_server, daemon=True).start()