Production-ready server configurations for enabling CORS in Nginx reverse proxies, Apache .htaccess mod_headers, and Cloudflare Edge Workers / Transform Rules.
Frequently Asked Questions
Q1. Why does Nginx lose CORS headers on 404 or 500 error responses?
By default, Nginx add_header only attaches to status codes 200, 201, 204, 206, 301, 302, 303, 304, 307, or 308. Adding the always parameter forces Nginx to send headers on all response codes including 400, 401, 403, 404, and 500.