title: Get Twitter userid from access token only
body: <p>This may be duplicated with other articles, but I can't figure out how to do it after reading all of those. </p>
  
  <p>I'm working on a back-end project in PHP and we are isolated from the front-end. According to the documentation from the front-end team, they will pass an access token and need the back-end to pull <code>userid</code> from Twitter's server. </p>
  
  <p>Is there any way to do it? I could pull the data if I have <code>oauth_signature</code> and <code>oauth_nonce</code>, but they only give us the access_token. </p>