HTTP headers / response header
Access-Control-Allow-Methods
Access-Control-Allow-Methods: GET, POST, PATCH
What it does
Preflight answer: which HTTP methods the cross-origin caller may use.
The gotcha
Only consulted on preflighted requests; forgetting PATCH here is the classic "PUT works but PATCH fails with CORS error".
Debugging headers on a phone
The fastest way to see what Access-Control-Allow-Methods is actually doing is to send the request and read both sides raw — ReqPad shows auto-generated and custom headers for every request, on all six protocols, with history. Related references: status codes · WWW-Authenticate · Content-Encoding · Transfer-Encoding · ETag · Last-Modified · Expires
Inspect Access-Control-Allow-Methods on a live request.
Build the request, send it, read raw headers and timing — from your iPhone. Free to start.