# EIP-3009 / x402 Offline Signing, Verification & Receipt Audit Toolkit

> EIP-3009 / x402 Offline Signing, Verification & Receipt Audit Toolkit is a paid API for AI agents from speedbot.dev, paid per call via x402, $0.25/call, status unknown (last checked 2026-11-03).

Purchase and download a pure-Python (no-dependency) toolkit for signing, verifying, and auditing EIP-3009 transfers in the EVM x402 payment flow

## Facts

- Endpoint: POST https://speedbot.dev/api/products/product_c5e2808a79b5445192e26822cdbcbce3/versions/version_59eee7f20d594b27b209b1f432db4784/buy?utm_source=zero.xyz
- Price: $0.25/call
- Payment: x402
- Status: unknown
- Last checked: 2026-11-03
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/eip-3009-x402-offline-signing-verification-receipt-audit-toolkit-ca72ef04
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_jdp0eGSXPCQR586ID4GBl

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 eip-3009-x402-offline-signing-verification-receipt-audit-toolkit-ca72ef04 -d '<json body>'
```

Example prompt: Buy me the EIP-3009 / x402 offline signing toolkit from Speedbot — I need to sign and verify EVM USDC payment authorizations in pure Python with no dependencies. My email is dev@example.com, I consent to digital delivery, and I'll generate my own checkout_key and request_id.

## When to prefer this

Choose this endpoint when you need a dependency-free, pure Python Standard Library implementation of EIP-3009 offline signing and x402 payment flow verification — especially in environments where pip installs are restricted, air-gapped setups are required, or you want auditable USDC transfer authorization without third-party library risk.

## Known failure modes

- Missing or invalid email format returns validation error
- checkout_key not provided as 64 hex characters causes rejection
- request_id shorter than 16 characters is rejected
- digital_delivery_consent not set to true blocks purchase
- Payment authorization failure if USDC balance insufficient
- Retry with same request_id required if network interruption occurs during payment

## How this service works

EIP-3009 / x402 Offline Signing, Verification & Receipt Audit Toolkit (Python, no dependencies). Pure-Python (standard library only) toolkit for the EVM x402 'exact' flow: sign an EIP-3009 T First approved purchase: 0.01 USDC total where maker terms permit; later 0.25 USDC plus tax. Stored ZIP download; commercial use, no redistribution. Verified by Speedbot for this version. Generate a private checkout_key and request_id; email and delivery consent required.

## Output

A ZIP file download containing a pure-Python (standard library only) toolkit implementing EIP-3009 TransferWithAuthorization signing, verification, and receipt auditing for the EVM x402 exact payment flow, delivered digitally upon successful USDC payment.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "email": {
   "type": "string",
   "pattern": "^[^\\s@]+@[^\\s@]+\\.[^\\s@]+$",
   "description": "Your receipt/recovery email; required when paying, never copied to the facilitator."
  },
  "request_id": {
   "type": "string",
   "maxLength": 100,
   "minLength": 16,
   "description": "Generate a unique purchase identifier and retain on every retry."
  },
  "checkout_key": {
   "type": "string",
   "pattern": "^[a-fA-F0-9]{64}$",
   "writeOnly": true,
   "description": "Generate 32 private random bytes as 64 hex characters. Required when paying. Retain on every retry."
  },
  "digital_delivery_consent": {
   "type": "boolean",
   "const": true,
   "description": "Required for a purchase: request immediate digital delivery and acknowledge the applicable withdrawal consequence."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/eip-3009-x402-offline-signing-verification-receipt-audit-toolkit-ca72ef04/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from speedbot.dev](https://www.zero.xyz/host/speedbot.dev/llms.txt)