Off the top of my head:<p><pre><code>  - Handling failure
  - Handling retries
  - DDoS prevention
  - Guaranteed ordering at scale (while handling failure and retries)
  - Handling stale endpoints
</code></pre>
...and several other issues.  It&#x27;s not that none of these are insurmountable, but there is a certain level of policy and engineering effort that goes into a web hook system, especially if it&#x27;s expected to operate at any sort of scale. I learned a lot watching the folks at GitHub build and maintain the web hook system while I was there.  It&#x27;s not as easy as it seems.