x402 conformance verification for wallet developers
x402 conformance verification for wallet developers. Pay $1.00 USDC on Base or Solana; receive an Ed25519-signed attestation that your client completed a real 402→auth→settle→deliver cycle on production infrastructure. Includes @maraventano/map decoder source (src/read.js) inline for URL parsing in future transactions. Use in CI pipelines, before SDK releases, or as agent-to-agent trust anchor.
Answeringour last check, 2026-10-10
1 of 1checks answered this week
646 msmedian answer time
$1.00listed price per call
$1.00price it asked us
Paid test badge: not yet. The checks above are free: we call the tool without paying and read the payment request it sends back. The Verified badge needs paid calls whose answers match the promised output, and nobody can buy a badge.
Endpoint
GET https://underground.substratesymposium.com/api/merchant-key
| Category | Commerce and shopping |
|---|---|
| Provider host | underground.substratesymposium.com |
| Networks | eip155:8453, solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp |
| Payment schemes | exact |
| Self-reported calls, 30 days | 1 from 1 payers (the provider's figure, not ours) |
Our checks, last 30 days
| Day | Result | HTTP | Asked | Time |
|---|---|---|---|---|
| 2026-10-10 | valid payment request | 402 | $1.00 | 646 ms |
Example input (from the provider)
{
"method": "GET",
"queryParams": {},
"type": "http"
}
Promised output schema (from the provider)
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": false,
"properties": {
"method": {
"enum": [
"GET"
],
"type": "string"
},
"queryParams": {
"properties": {},
"type": "object"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method"
],
"type": "object"
},
"output": {
"properties": {
"example": {
"type": "object"
},
"type": {
"type": "string"
}
},
"required": [
"type"
],
"type": "object"
}
},
"required": [
"input"
],
"type": "object"
}