CORS Tester
Preflight Simulator & Diagnosis
History
Request Configuration
Endpoint URL
Method
GET
POST
PUT
DELETE
PATCH
OPTIONS
Custom Headers
+ Add
✕
Test CORS
Preflight Only
Request Flow
Results
Suggested Server Configuration
Express
Nginx
Flask
Copy
Common Scenarios
🌐
REST API (GET)
JSONPlaceholder
📤
POST with JSON
httpbin.org
🐙
GitHub API
Public user data
🚫
Blocked CORS
No CORS headers
Testing CORS…