I sought in Internet how to determine from Google response whether an access token is expired. I found no definitive answer. So, finally I created an access token and waited for a hour to see the Google response when I try to use this token. The Google response (with a partial list of HTTP headers) is below: HTTP/1.1 401 Unauthorized WWW-Authenticate: Bearer realm=”https://accounts.google.com/”, error=invalid_token Content-Type: … Continue reading Expired access token in Google OAuth