title: What is an appropriate HTTP status code for a flow where a client is asked for more information before proceeding?
body: <p>We have a single page application which has a series of forms required to process a complete "new application".</p>
  
  <p>Steps like "enter email", "verify email", "verify mobile number", etc</p>
  
  <p>The flow of the steps is based on the previous step and can vary based on the user's journey (where they came from, what they've provided, etc).</p>
  
  <p>This process is orchestrated by the server by the client hitting a <code>/continue</code> endpoint.</p>
  
  <p>The user journey can vary e.g.</p>
  
  <pre><code>Step 1 -&gt; Step 2 -&gt; Step 4 -&gt; Step 5 -&gt; Complete
  Step 1 -&gt; Step 2 -&gt; Step 3 -&gt; Complete
  Step 1 -&gt; Step 2 -&gt; Step 3 -&gt; Step 4 -&gt; Step 5 -&gt; Complete
  </code></pre>
  
  <p>On each step, the <code>/continue</code> endpoint will return the next required step of the process until there are no steps left, at which point it will resolve a <code>204</code>.</p>
  
  <p>When the user is required to complete an action before continuing, we tell the SPA what page to display by issuing a <code>requiredAction</code> in the response</p>
  
  <pre><code>{
      "requiredAction": "STEP_3"
  } 
  </code></pre>
  
  <p>The question is, what is the appropriate status code for requesting more stuff from the client?</p>
  
  <p>I see that <code>303</code> might be as in the <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/303" rel="nofollow noreferrer">specification</a> it states that it:</p>
  
  <blockquote>
    <p>indicates that the redirects don't link to the newly uploaded resources but to another page, like a confirmation page or an upload progress page.</p>
  </blockquote>