title: Obtaining Chrome Extension ID for development
body: <p>Although similar to <a href="https://stackoverflow.com/questions/21497781/how-to-change-chrome-packaged-app-id-or-why-do-we-need-key-field-in-the-manifest">this SO question</a>, I am not asking:</p>
  
  <blockquote>
    <p>Under what conditions does an extension's ID change?</p>
  </blockquote>
  
  <p>nor</p>
  
  <blockquote>
    <p>How can I upload my zip archive to the Chrome Dashboard?</p>
  </blockquote>
  
  <p>I am however asking, how I can obtain an extension's key without using the Chrome Dashboard. Therefore, I do not consider it a duplicate of <a href="https://stackoverflow.com/questions/21497781/how-to-change-chrome-packaged-app-id-or-why-do-we-need-key-field-in-the-manifest">this SO question</a>.</p>
  
  <p>The <a href="https://developer.chrome.com/apps/app_identity#copy_key" rel="noreferrer">documentation for using Google Identity</a> inside a Chrome extension states the need to copy an extensions's key to its manifest file.</p>
  
  <blockquote>
    <p><em>To keep your application ID constant, you need to copy the key in the
    installed manifest.json to your source manifest.</em></p>
  </blockquote>
  
  <p>However, when navigating to the <a href="http://www.chromium.org/user-experience/user-data-directory" rel="noreferrer">recommended directory</a> (...<code>Google/Chrome/Default/Extensions</code>) I do not see the ID of my unpacked extension. I realise this is because the extension was not installed as <a href="https://developer.chrome.com/extensions/crx" rel="noreferrer">.crx file</a>. However, the <a href="https://developer.chrome.com/apps/app_identity#copy_key" rel="noreferrer">documentation</a> is clearly written for the purposes of <em>development</em>:</p>
  
  <blockquote>
    <p><em>Copy key in the installed manifest.json to your source manifest, so
    that <strong>your application ID will stay constant during development</strong>.</em></p>
  </blockquote>
  
  <p>How can I avoid packaging my extension and reinstalling each time I make a change? 
  If my development extension has no installed manifest file from which I can obtain the extension's key, where can I get it from?</p>