The second line of “The Zen of Python” (try import this) says “Explicit is better than implicit.”. By default Flask response does not return any cache header and you can suppose that browsers will not cache, but some of them can decide for you. So it’s better to provide them, especially for API and it’s easy:

	@app.after_request
    def set_response_headers(response):
        response.headers['Cache-Control'] = 'no-cache, no-store, must-revalidate'
        response.headers['Pragma'] = 'no-cache'
        response.headers['Expires'] = '0'
        return response