# Synthex Forge x402 Receipt Check

> Synthex Forge x402 Receipt Check is a paid API for AI agents from x402.synthexforge.com, paid per call via x402, $0.05/call, status unknown (last checked 2026-10-23).

Verifies that a payment receipt satisfies a given offer, returning a signed attestation of validity for x402 micropayment flows on Base mainnet

## Facts

- Endpoint: POST https://x402.synthexforge.com/v1/bureau/receipt-check?utm_source=zero.xyz
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-23
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/synthex-forge-x402-receipt-check-567f7838
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Kp2gzsenckllzYLXjDaF2

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 synthex-forge-x402-receipt-check-567f7838 -d '<json body>'
```

Example prompt: Can you check whether this payment receipt I got satisfies the offer I advertised — verify it's a valid x402 USDC receipt on Base mainnet before I unlock the resource?

## When to prefer this

Choose this endpoint when you need to cryptographically verify that an x402 v2 payment receipt satisfies a specific offer before granting access to a paid resource. It is the right choice when your system acts as a payee receiving USDC on Base mainnet and needs an independent, signed attestation of receipt validity rather than doing on-chain verification yourself.

## Known failure modes

- Receipt does not match the offer (ok: false)
- Malformed receipt or offer object causes a 400 error
- Payment was on the wrong chain (not Base mainnet, chain ID 8453)
- Expired or already-used receipt returns invalid
- 402 Payment Required returned if the caller hasn't paid the $0.05 USDC verification fee
- Network timeout or upstream signing service unavailable

## How this service works

Synthex Forge x402 Receive: 41 paid verification, attestation and governance endpoints (Ed25519 + SHA-256 signed artifacts) plus free verify/public-key/standard sibling routes. Paid routes answer HTTP 402 with an x402 v2 `payment-required` envelope (atomic USDC on Base mainnet, chain ID 8453). Free routes are declared with `security: []` per the x402scan discovery spec.

## Output

Returns a JSON object with an `ok` boolean indicating whether the receipt is valid and satisfies the provided offer. On success, `ok` is true; on failure, `ok` is false, potentially with error details about the mismatch.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "offer": {
   "type": "object",
   "description": "The advertised offer the receipt should satisfy"
  },
  "receipt": {
   "type": "object",
   "description": "The payment receipt under test"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/synthex-forge-x402-receipt-check-567f7838/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.synthexforge.com](https://www.zero.xyz/host/x402.synthexforge.com/llms.txt)