socket.help

CORS tester

Check cross-origin headers and preflight responses.

Runs on the server
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Your result will appear hereAdd your input, choose the options and run the tool.

This check runs on the server. Input and results are not saved as execution history; hosted allowances apply.

Guide & examples

About CORS tester

Send a public preflight request and inspect CORS response headers for a chosen origin, method, and header set.

When to use it

Diagnose an API’s preflight configuration.

CORS tester example
OPTIONS with Origin and Access-Control-Request-Method

How to use it

  1. Enter a URL and the intended request context.
  2. Inspect the returned preflight headers and checks.

Limits & privacy

Only public HTTP/HTTPS targets on ports 80, 443, 8080, or 8443. Private, loopback, link-local, and reserved IP ranges are blocked on every hop. Up to five redirects, 256 KiB response data, and a ten-second overall deadline. No cookies or user credentials are sent. No cookies are sent. Header checks are diagnostic and do not replace a complete browser integration test.

Use this tool from the API reference or connect through the SDK, CLI, SSH, or MCP. Hosted calls share your plan allowances.