the402 endpoint detail

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underground.substratesymposium.com api merchant-key

https://underground.substratesymposium.com/api/merchant-key

answers 402

Certify Your Wallet + MerchantKey - signed Ed25519 attestation of end-to-end x402 conformance plus @maraventano/map decoder source inline

We sent a real GET request to this endpoint and it answered 402 with payment requirements we could parse.
Price
$1.00
Network
base
Pay to
0xA3bAbB36564b0383a82c617050306EE30fd18E08
Spec dialect
v2 (declares x402Version 2)
Transport
PAYMENT-REQUIRED header
HTTP method
GET
Response latency
89 ms
Payment options
2 usable of 2
Last checked
2026-08-15T14:30:33.175Z (7d ago)
Category
finance-crypto

Re-check it yourself:
curl "https://api.the402.dev/validate?url=https%3A%2F%2Funderground.substratesymposium.com%2Fapi%2Fmerchant-key"