# vAPI x402 Decoder

> vAPI x402 Decoder is a paid API for AI agents from api-staging.vapinetwork.ai, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Decodes and explains what an EIP-712 typed EVM payment authorization actually permits before the user signs it.

## Facts

- Endpoint: POST https://api-staging.vapinetwork.ai/x402/decode
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/vapi-x402-decoder-2c20a13b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_XTarvX-hEZBqqyqKx0DVf

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 vapi-x402-decoder-2c20a13b -d '<json body>'
```

Example prompt: Before I sign this x402 payment request, decode this EIP-712 typed data for me so I can see exactly what amount, recipient, and conditions it's authorizing: {paste EIP-712 JSON here}.

## When to prefer this

Use this endpoint when an AI agent or user needs to inspect the contents of an x402 EIP-712 payment authorization before signing, particularly to audit what amount, recipient, and conditions are being approved. Prefer this over manual EIP-712 parsing when you need a fast, structured, human-readable breakdown of a payment payload without building your own decoder.

## Known failure modes

- Malformed or invalid EIP-712 JSON string returns a parse error
- Unsupported EIP-712 domain or type structure may yield incomplete decoding
- Missing required typedData field returns a validation error
- Signature provided without matching typedData may produce inconsistent results
- Staging environment may have reduced availability or changed behavior

## How this service works

Decode what an EVM payment authorization actually authorizes before signing.

## Output

A human-readable breakdown of what the EIP-712 typed data authorizes, including the payment amount, recipient address, token, conditions, and other relevant fields extracted from the structured payment authorization payload.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "signature": {
   "type": "string"
  },
  "typedData": {
   "type": "string",
   "description": "JSON string of the EIP-712 typed data"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/vapi-x402-decoder-2c20a13b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api-staging.vapinetwork.ai](https://www.zero.xyz/host/api-staging.vapinetwork.ai/llms.txt)