← All endpoints
cors-header-checker.underscoredone.com check
https://cors-header-checker.underscoredone.com/check
answers 402
Sends a real request to any URL you provide, attaches an Origin header, and reads back all six standard cross-origin permission headers the server returns. Tells you whether cross-origin requests are enabled at all, whether your specific origin is permitted, and shows you every permission value exactly as the server sent it. Perfect for figuring out why a browser is blocking a request, confirming
We sent a real
POST request to this endpoint and it
answered 402 with payment requirements we could parse.
- Price
- $0.01
- Network
- base
- Pay to
- 0xE9740820225B3918b4ddd1292C7cA4Ca0e2C2F08
- Spec dialect
- v2 (declares x402Version 2)
- Transport
- PAYMENT-REQUIRED header
- HTTP method
- POST
- Response latency
- 138 ms
- Payment options
- 2 usable of 2
- Last checked
- 2026-08-15T14:22:50.711Z (1h ago)
- Category
- finance-crypto
Re-check it yourself:
curl "https://api.the402.dev/validate?url=https%3A%2F%2Fcors-header-checker.underscoredone.com%2Fcheck"