title: Azure API Management - Authentication: OAuth2 vs Certificate
body: <br>
  I would like to have your mind about an implementation. Thank you in advance for any suggestion :)
  <br><br>**Scenario**<br>
  I have a set of APIs. They are accessible via REST and protected by OAuth2. I have also a list of machines that needs to access them. 
  Question
  On machine’s side, which is the best solution to access them? Should I implement a client certificate authentication or OAuth2 is a suitable solution?<br>
  <br>**My doubts:**<br>
  <ul>
  <li>In case of hundreds, thousands of machines, the certificate
  management become too complex/costly?<br></li>
  <li>Should I use a certificate for each machine or one certificate for more than one?</li>
  <li>How can I deploy smartly the certificate to each machine?</li>
  </ul>
  <p>I like the idea to have the mutual authentication, but I’m afraid is to heavy to maintain compared to the OAuth structure. I plan to use Microsoft Azure as cloud service.<br>
  Thanks!</p>