I've been trying to send data from flask over socket io. I need to access this data from a different origin, but it is giving a CORS error. I have tried using all kinds of cross origin stuff and none of it has worked. Can somebody help with this. The view that should be called thought socket io: from flask.ext.cors import cross_origin @socketio.on('increment',namespace="/api") @cross_origin() def increment(message): number += 1; emit('number',{'data':number},broadcast=True) Running the server: app = Flask(__name__) cors = CORS(app,resources={r"/api/*":{"origins":"*"}}) socketio = SocketIO(app) app.debug = True app.host = '0.0.0.0' socketio.run(app) Continue reading...