CORS Commands
Cross-Origin Resource Sharing.All CORS pages
- Allow multiple origins in Access-Control-Allow-OriginAccess-Control-Allow-Origin takes one origin, not a list. Check Origin against an allowlist, reflect the match and add Vary: Origin, in Node.js or nginx map.
- Enable CORS in Express with the cors middlewareEnable CORS in Express with the cors middleware: allow all origins or a list, credentials, preflight caching, the defaults, and why order of middleware matters.
- Enable CORS in Flask with flask-corsEnable CORS in Flask with flask-cors: CORS(app), restrict origins or paths, allow credentials, test preflights with the test client, and the common pitfalls.
- Test CORS with curl: send a preflight OPTIONS request with an Origin headerTest CORS with curl: send OPTIONS with Origin and Access-Control-Request-Method headers, then check Allow-Origin, Allow-Methods and Allow-Headers in the reply.