# agentbit.app x402 Endpoint & Payment Header Linter

> agentbit.app x402 Endpoint & Payment Header Linter is a paid API for AI agents from agentbit.app, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Validates x402 payment endpoints and payment headers against the v2 spec, catching EIP-712 domain name mismatches, CAIP-2 errors, expired authorizations, and Coinbase Bazaar indexing requirements.

## Facts

- Endpoint: POST https://agentbit.app/v1/x402/inspect
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agentbit-app-x402-endpoint-payment-header-linter-db1092df
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_i826F1JCa8Jx2MG3rVfut

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 agentbit-app-x402-endpoint-payment-header-linter-db1092df -d '<json body>'
```

Example prompt: Can you lint my x402 payment endpoint at https://myapi.example.com/premium-data to check for EIP-712 domain name issues, CAIP-2 errors, and whether Coinbase Bazaar indexing extensions are present?

## When to prefer this

Choose this endpoint when debugging x402 payment integrations, specifically for catching EIP-712 domain name mismatches ('USD Coin' vs 'USDC'), CAIP-2 network ID errors, Coinbase Bazaar indexing extension requirements, expired authorizations, or malformed payment headers. Prefer this over manual inspection when you need production-validated rules derived from real facilitator behavior, not just spec text.

## Known failure modes

- Endpoint URL is unreachable or returns non-402 status — probe cannot complete
- Malformed base64 input for payment_payload or payment_required — parse error returned
- x402 endpoint times out — finding may be incomplete
- Network connectivity issues reaching the target URL
- No input provided (url, payment_payload, or payment_required required) — validation error

## How this service works

Lint any x402 endpoint or payment header against the v2 spec and real CDP facilitator behavior: CAIP-2 network ids, atomic amounts, the EIP-712 domain-name trap ('USD Coin' on Base mainnet vs 'USDC' on Sepolia — wrong name = every settlement fails), the extensions echo Coinbase Bazaar requires for indexing, expired authorizations. Findings as error/warning/info with what will actually break. Built by a seller that debugged all of these in production.

## Output

A JSON object containing a verdict (pass/fail), mode (live-probe or offline), per-category counts of errors/warnings/infos, a list of findings each with a code, severity level, and human-readable message explaining what will break and why, plus the HTTP status and number of accepted payment options.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "description": "A paid x402 endpoint to probe live (GET, expects the 402 envelope)"
  },
  "payment_payload": {
   "type": "string",
   "description": "Base64 PAYMENT-SIGNATURE header value to lint the client payload (optionally alongside payment_required)"
  },
  "payment_required": {
   "type": "string",
   "description": "Base64 PAYMENT-REQUIRED header value to lint offline"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "url": "https://agentbit.app/v1/web/search",
  "mode": "live-probe",
  "counts": {
   "infos": 1,
   "errors": 0,
   "warnings": 0
  },
  "verdict": "pass",
  "findings": [
   {
    "code": "EIP712_DOMAIN_OK",
    "level": "info",
    "message": "accepts[0]: extra.name matches USDC on Base mainnet."
   }
  ],
  "http_status": 402,
  "accepts_count": 1
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agentbit-app-x402-endpoint-payment-header-linter-db1092df/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentbit.app](https://www.zero.xyz/host/agentbit.app/llms.txt)