I figured it out. The first request is a CORS pre-flight request that CORS uses to validate first that the server can handle the request. The WebServer library only supports GET and PUT requests supposedly but processes that preflight check as well.

I added the following code to my request ...

I built a web server on an ESP32 device using the Arduino-ESP32 WebServer.h library. The server works great, but I noticed that every request that comes in through the browser processes twice on the server. When I send the same request from Postman, it only processes once. I tried this on a variety ...