Tool: CORS Header Analyzer

[lovestaco]

CORS Header Analyzer

This issue is reserved for first-time contributors. If you’ve never made a pull request to open source before, this one’s for you! Don’t worry if it feels tricky — I’ll guide you through the process step by step. 🌟

Problem Statement

CORS (Cross-Origin Resource Sharing) is often misconfigured in APIs, causing confusing errors for frontend developers. Existing tools are limited, outdated, or not user-friendly.

We need a simple, open-source CORS Header Analyzer that helps developers and teams test and understand their API’s CORS setup.

Proposed Solution

Implement a tool that can:

• ✅ Test Access-Control-Allow-Origin against given domains.
• ✅ Show allowed HTTP methods (GET, POST, PUT, etc.).
• ✅ Detect wildcard (*) vs exact domain matches.
• ✅ Provide security insights (e.g., risks of *, missing OPTIONS, credentialed request concerns).

Alternative Solutions

Existing open-source tools for reference:

• mscoutermarsh/cors-test
• njgibbon/nicks-cors-test

This project aims to offer a more integrated, actively maintained, and developer-friendly solution.

Additional Context

This will help:

• Developers debug API endpoints.
• Security engineers catch misconfigurations.
• Beginners learn how CORS policies affect client-side apps.

UI Inspiration

• Live Demo: cors-test.codehappy.dev

Article / Documentation Ideas

Alongside the tool, we could publish educational content:

• Preflight requests (OPTIONS) explained
• Credentialed requests (withCredentials, cookies)
• Common misconfigurations with Access-Control-Allow-Origin
• How browsers enforce vs how servers configure CORS

Use Cases

• A frontend dev testing their app against an API.
• A team lead reviewing backend headers for security.
• Students experimenting with APIs and browser requests.

Related Issues

None yet — this is a new feature proposal.

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I'm happy to hold your hand through this if you need help. Catch me on discord.

https://hexmos.com/freedevtools/t/

[Janmesh23]

hi @lovestaco !
can i take up this issue , i would get to learn alot about CORS and other related stuff. \

[lovestaco]

Sure @Janmesh23

[lovestaco]

You can refer to the CONTRIBUTING.md for further instructions.

Also, we have a Discord channel you can join if you need any kind of input — the community is very friendly and helpful.
You can dm me(lovestaco in Discord) as well.