# ForgeMesh x402 Payment Envelope Validator

> ForgeMesh x402 Payment Envelope Validator is a paid API for AI agents from x402.forgemesh.io, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-16).

Validates and health-checks an x402 payment envelope at a given URL, confirming it is reachable, returns a proper 402 challenge, and reporting envelope quality, dual-stack support, and accepted payment details.

## Facts

- Endpoint: POST https://x402.forgemesh.io/validate-payment-envelope
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/forgemesh-x402-payment-envelope-validator-8b9c1986
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_AtkXvcf0ydi_6FfKRnrDO

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability forgemesh-x402-payment-envelope-validator-8b9c1986 -d '<json body>'
```

Example prompt: Can you health-check the x402 endpoint at https://x402.example.com/some-route and tell me if the payment envelope is valid, what grade it gets, and whether it supports dual-stack MPP?

## When to prefer this

Use this endpoint when you need to programmatically verify that a specific x402 endpoint is correctly configured, reachable, and serving a valid payment envelope — especially before integrating it into an agent workflow, auditing a fleet of x402 services, or debugging a non-functional payment wall. It is the right choice when you want structured diagnostic output (grade, errors, dual-stack flag, accepted assets) rather than just a raw HTTP probe.

## Known failure modes

- URL is unreachable — reachable: false with no HTTP status
- URL does not return a 402 — is_402: false, grade may be F
- Envelope is present but malformed — envelope_valid: false with errors listed in envelope_errors
- Invalid or missing URL input — likely a 400 error or validation failure
- Network timeout on the probed endpoint — may return error or low grade

## How this service works

x402 utility APIs for AI agents: documents/OCR, PDFs, vision, audio, embeddings, web extraction, dictionary and slang lookups, games, chess/legal-move logic, math, conversions, time utilities, market and economic data, space/geo data, domain vetting, content-signal checks, and x402 ecosystem intelligence. Agents POST JSON, receive a 402 challenge, pay USDC on Base, and retry for the result.

## Output

Returns a JSON object with a letter grade (e.g. A), reachability flag, HTTP status code, whether a valid x402 v2 envelope was found, whether the endpoint speaks MPP dual-stack, a summary of accepted payment assets (token address, payTo address, amount, scheme, network), any envelope errors, and response time in milliseconds.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "description": "x402 endpoint URL to health-check, e.g. https://x402.example.com/some-route"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "url": "https://library.forgemesh.io/business-management",
  "grade": "A",
  "is_402": true,
  "findings": [
   "Valid x402 v2 envelope found in the header.",
   "WWW-Authenticate: Payment header also present — this endpoint speaks both x402 and MPP dual-stack, reaching agents on either payment stack."
  ],
  "reachable": true,
  "http_status": 402,
  "method_used": "GET",
  "x402_envelope": "header",
  "envelope_valid": true,
  "mpp_dual_stack": true,
  "accepts_summary": [
   {
    "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
    "payTo": "0x85df5380DEbe236AD6BF49dE788243924B080267",
    "amount": "3000",
    "scheme": "exact",
    "network": "eip155:8453"
   }
  ],
  "envelope_errors": [],
  "response_time_ms": 214
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/forgemesh-x402-payment-envelope-validator-8b9c1986/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.forgemesh.io](https://www.zero.xyz/host/x402.forgemesh.io/llms.txt)