CORS Header Generator
Generate correct CORS headers for raw HTTP, Nginx, Apache or Express — no more preflight errors.
Runs 100% in your browser — nothing is ever uploaded.
What is CORS Generator?
This free CORS header generator helps you fix cross-origin errors fast. Set the allowed origin, HTTP methods, request headers, credentials flag and preflight max-age, then get the exact configuration in four formats: raw response headers, Nginx add_header directives with an OPTIONS handler, Apache Header set lines, or an Express cors() middleware snippet. Everything is generated locally in your browser.
How to use CORS Generator
- Open the tool — no signup, no upload, everything runs in your browser.
- Fill in the CORS options in the form; sensible defaults are pre-selected.
- The header output updates instantly with every change you make.
- Copy the result or download it as a ready-to-use file.
Frequently asked questions
Is this CORS generator free to use?
Yes — this CORS generator is completely free with no signup, no limits, and no watermarks. Use it as often as you like.
Why can't I use a wildcard origin with credentials?
The CORS spec forbids Access-Control-Allow-Origin: * when Access-Control-Allow-Credentials is true. Browsers will block the response — you must echo the exact requesting origin instead of the wildcard.
Is my configuration data private?
Absolutely. Everything is generated locally in your browser with JavaScript — no data, settings, or file contents are ever sent to any server.
Do these tools touch my servers?
No. OpsForge tools are pure calculators and generators that run in your browser — they never connect to your infrastructure. You copy the result and apply it yourself.
Is the chmod calculator accurate for all systems?
Yes — octal permission notation is a POSIX standard, so the results apply identically on Linux, macOS and BSD.
Will more DevOps tools be added?
Yes — Dockerfile, docker-compose, nginx and CI config generators are on the roadmap. Everything will stay free and client-side.