CORS Checker

Check the CORS headers of the API endpoint

Check CORS

CORS What is the size?

CORS (Cross-Origin Resource Sharing) is a security mechanism that allows or blocks requests from another domain.

When the browser sends a request to an API in a different domain, the server needs to return appropriate CORS headers for the browser to allow the response.

CORS Checker - Free Online CORS Headers Checking Tool

CORS Checker is a free online tool to check CORS (Cross-Origin Resource Sharing) headers of API endpoints. Debug CORS errors quickly, view details of Access-Control-Allow-Origin, Access-Control-Allow-Methods, Access-Control-Allow-Headers and other CORS headers. CORS is an important browser security mechanism, controlling resource sharing between different domains. CORS errors are one of the most common problems when developing frontends that call APIs from backends in different domains. This tool helps developers quickly identify the cause and how to fix it.

Outstanding features

Check the CORS headers of any API endpoint
Full display of Access-Control-Allow-Origin header
See Allowed Access-Control-Allow-Methods
Check Access-Control-Allow-Headers
Show Access-Control-Allow-Credentials
Xem Access-Control-Max-Age (cache preflight)
Check Access-Control-Expose-Headers
Supports all HTTP methods: GET, POST, PUT, DELETE, PATCH, OPTIONS
Customize Origin header to test from specific domain
Detailed explanation of CORS and how it works

Why Need to Check CORS Headers?

CORS (Cross-Origin Resource Sharing) is a browser security mechanism that prevents JavaScript from domain A from calling domain B's API without permission. When encountering error

Benefits when used

  • •Debug CORS errors in seconds instead of hours
  • •Understand the server's CORS configuration
  • •Determine the exact headers to add
  • •Test CORS from many different origins
  • •Save time on frontend development
  • •Communicate effectively with backend developers
  • •Avoid production errors due to CORS misconfiguration
  • •Learn and deeply understand the CORS mechanism

Instructions for Using CORS Checker

  1. 1Enter the full URL of the API endpoint to test
  2. 2Enter Origin - the domain you want to test calling the API from
  3. 3Choose the appropriate HTTP Method (GET, POST, PUT, DELETE...)
  4. 4Click
  5. 5to send preflight request
  6. 6See the results: blue = CORS enabled, red = CORS blocked
  7. 7Check each header in detail to know what needs to be configured on the server

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