How to use this developer tool
- Paste or upload the expected source text.
- Review any options shown below the input.
- Select Build CORS Config or press Ctrl/Cmd + Enter.
- Check the notes, then copy or download the output.
CORS Configuration Builder
Build a CORS response-header draft and matching Express middleware configuration from an explicit list of allowed origins. Options cover methods, credential support, and preflight caching while preventing the invalid wildcard-plus-credentials combination. The builder produces configuration text only and does not change a server. CORS is a browser access control mechanism, not authentication, authorization, CSRF protection, or a firewall.
Developer Input
CORS allowlistAd space
What this developer tool does
CORS Configuration Builder turns the entered source into a structured or generated result that can be inspected before use.
Validates absolute HTTP(S) origins, applies selected methods and credential settings, and emits headers plus an Express cors options example.
Input stays in this browser tab. Always remove live secrets before sharing screenshots or downloaded results.
Example
Input
https://app.example.com https://admin.example.com
Running the sample produces output that reflects the parsed fields and reports any unsupported or security-sensitive detail.
Use cases
- Translate copied API documentation into project code.
- Inspect request, response, or header configuration during debugging.
- Create a reviewable draft for tests and documentation.
- Spot malformed, duplicate, or overly broad values before deployment.
Tips for reliable output
- Remove real tokens, cookies, and API keys before pasting.
- Keep quoted values intact when copying shell commands.
- Read warnings instead of assuming every option was converted.
- Test generated code against a staging endpoint first.
- Review browser and server security rules separately.
Processing details
Validates absolute HTTP(S) origins, applies selected methods and credential settings, and emits headers plus an Express cors options example. Processing is deterministic except where cryptographic random values are intentionally generated.
This browser tool does not execute remote requests, expand shell variables, inspect server behavior, or replace application-specific security review.
Frequently asked questions
Does CORS Configuration Builder send my input to a server?
No. Processing runs in the browser and the page does not transmit the entered text.
What input does CORS Configuration Builder support?
Enter allowed origins, one per line using the syntax shown in the sample.
Can I use the generated output in production?
Use it as a reviewed starting point. Environment-specific security, authentication, and error handling still need verification.
Why might CORS Configuration Builder report a limitation?
The parser handles documented common syntax and reports constructs that would require shell, browser, or server context.
How can I verify the CORS Configuration Builder result?
Compare the parsed URL, headers, body, directives, or origins with the source and test the final configuration in a non-production environment.
Related developer tools
Output fields
| Field | Meaning |
|---|---|
| Output | Generated or parsed text |
| Summary | Counts and completion state |
| Notes | Warnings and review guidance |
HTTP & Security Headers
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