title: application/x-www-form-urlencoded or multipart/form-data?
body: <p>In HTTP there are two ways to POST data: <code>application/x-www-form-urlencoded</code> and <code>multipart/form-data</code>. I understand that most browsers are only able to upload files if <code>multipart/form-data</code> is used. Is there any additional guidance when to use one of the encoding types in an API context (no browser involved)? This might e.g. be based on:</p>
  
  <ul>
  <li>data size</li>
  <li>existence of non-ASCII characters</li>
  <li>existence on (unencoded) binary data</li>
  <li>the need to transfer additional data (like filename)</li>
  </ul>
  
  <p>I basically found no formal guidance on the web regarding the use of the different content-types so far.</p>