title: How to correctly encode special characters in multipart/form-data POST request
body: <p>I am working on fetching the waste disposal data from our local waste disposal service, it took quite a while to understand the API (there is no official API or documentation and no one responds to a email).</p>
  
  <p>The API is working now, but I am having issues with special characters with <code>ä, ö and ü</code>.</p>
  
  <p>I am using <code>PHP</code> and <code>curl</code> to make the requests, requests without such characters work flawlessly.</p>
  
  <p>I copied the <code>curl</code> request from Chrome and executed it in the Terminal, it worked, but I saw, that <code>ä</code> has been encoded to <code>\xe4</code>, in PHP however the <code>ä</code> gets encoded to <code>\u00e4</code> and PHP doesn't work.</p>
  
  <p>If I change the <code>ä</code> directly to <code>\xe4</code> it won't work either.</p>
  
  <p>Is there a specification for encoding such characters in a <code>multipart/form-data</code> <code>POST</code> request I am missing?</p>