# ReceiptStamp Proof-of-Execution Notary

> ReceiptStamp Proof-of-Execution Notary is a paid API for AI agents from receiptstamp.panmediatech.workers.dev, paid per call via x402, $0.02/call, status unknown (last checked 2026-09-14).

Stamps an arbitrary payload with a cryptographically signed receipt (ed25519-sha256 hash, timestamp, signature, keyId) to prove execution occurred at a specific moment.

## Facts

- Endpoint: POST https://receiptstamp.panmediatech.workers.dev/x402/stamp
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/receiptstamp-proof-of-execution-notary-f735ef98
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Smil8HlqRPbjBFJyKrIuB

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 receiptstamp-proof-of-execution-notary-f735ef98 -d '<json body>'
```

Example prompt: Can you notarize this payload for me — stamp it with an ed25519-signed receipt so I have a verifiable hash, timestamp, and signature I can check against the public key later?

## When to prefer this

Choose this endpoint when you need a lightweight, independent, third-party cryptographic proof-of-execution receipt with a verifiable ed25519 signature — especially in agentic workflows where auditability and non-repudiation of actions matter. Prefer it over self-signed timestamps or centralized notaries when you want a publicly verifiable signature against a known public key.

## Known failure modes

- Empty or missing payload may return an error or produce a receipt over an empty body
- Payment not provided or insufficient USDC ($0.02) returns a 402 Payment Required response
- Malformed request may return a 4xx error
- Service unavailability on Cloudflare Workers edge returns a 503

## How this service works

Signed proof-of-execution notary for AI agents: POST a payload, get hash + timestamp + signature receipt verifiable via /pubkey. Independent attestation for agent jobs and tool outputs. Pay-per-stamp x402 USDC on Base. Not custody, escrow, or delivery verification.

## Output

Returns a receipt object containing: a SHA-256 hash of the payload, an ISO timestamp, an ed25519 signature over the hash and timestamp, the keyId identifying the signing key, and the algo string 'ed25519-sha256'. The signature can be independently verified against the public key at /pubkey.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/receiptstamp-proof-of-execution-notary-f735ef98/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from receiptstamp.panmediatech.workers.dev](https://www.zero.xyz/host/receiptstamp.panmediatech.workers.dev/llms.txt)