Hi, one of the authors here. Correct, we added that to the protocol FAQ too: <a href="https:&#x2F;&#x2F;github.com&#x2F;tus&#x2F;tus-resumable-upload-protocol&#x2F;blob&#x2F;master&#x2F;protocol.md#why-are-you-not-using-the-x--prefix-for-your-headers" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;tus&#x2F;tus-resumable-upload-protocol&#x2F;blob&#x2F;ma...</a><p>The only exception is X-HTTP-Method-Override, as people have been standardizing on this, and the header is specifically meant to let people deploy tus in environments that don&#x27;t support all of HTTP and are apparently hard to change.