Security & Web Utilities • Published August 18, 2026

Debugging CORS with cURL, Postman & Chrome DevTools: The Ultimate Diagnostic Guide

Learn how to simulate and debug CORS preflight requests using cURL command line and Chrome DevTools Network inspector.

Step-by-step diagnostic recipes to test and simulate CORS preflight OPTIONS requests using cURL and Chrome DevTools Network inspection.

Frequently Asked Questions

Q1. Why does cURL not show a CORS error when my browser does?

cURL is an HTTP client, not a web browser. It does not enforce the browser Same-Origin Policy. To test CORS with cURL, you must explicitly simulate browser headers using -H "Origin: ..." and inspect the returned Access-Control- headers.