title: Running in-browser development server [like stackblitz/codesandbox]
body: <h1>The Question:</h1>
  <p><strong>How to run a live in-browser dev server?</strong></p>
  <hr />
  <h3>Context</h3>
  <p><a href="https://stackblitz.com/" rel="nofollow noreferrer">Stackblitz</a> and <a href="https://codesandbox.io" rel="nofollow noreferrer">CodeSandbox</a> are two platforms that provide online IDE to develop web applications. I have a similar use case, and would need to run an in browser dev server, but there's not much that I was able to find, apart from these few observations.</p>
  <hr />
  <h3>Few Observations</h3>
  <ol>
  <li><p>Stackblitz, in their <a href="https://medium.com/@ericsimons/stackblitz-online-vs-code-ide-for-angular-react-7d09348497f4" rel="nofollow noreferrer">announcement post</a> describe that they use, <em>&quot;Progressive Web App API’s to run a live dev server in-browser.&quot;</em></p>
  </li>
  <li><p>To resolve node dependencies stackblitz uses their custom npm client <a href="https://github.com/stackblitz/core/tree/master/turbo-cdn" rel="nofollow noreferrer">turbo</a> . On the github repo page, it is described as</p>
  </li>
  </ol>
  <blockquote>
  <p>Express.js routes used for hydrating client-side dependencies and type definitions on StackBlitz.</p>
  </blockquote>
  <ol start="3">
  <li>There is also some module bundler involved to support live development with hot-reloading.</li>
  </ol>
  <hr />
  <p>I <em>suspect</em> stackblitz runs an express.js server in the service worker, but i can't seem to understand how. I'm out of ideas here, any help would be appreciated.</p>