With the Flask-CORS module, you can do cross-domain requests without changing your code.

from flask.ext.cors import CORS

app = Flask(__name__)
cors = CORS(app, resources={r"/api/*": {"origins": "*"}})

• https://pypi.python.org/pypi/Flask-Cors
• https://github.com/corydolphin/flask-cors

Update

As Eric suggested, the flask.ext.cors module is now deprecated, you should rather use the following code:

from flask_cors import CORS

app = Flask(__name__)
cors = CORS(app, resources={r"/api/*": {"origins": "*"}})