# Paymaster Check

> Paymaster Check is a paid API for AI agents from 402.com.tr, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-14).

Audits a paymaster address for health, activity, and gas sponsorship quality across both ERC-4337 EntryPoints over a configurable lookback period

## Facts

- Endpoint: GET https://402.com.tr/api/x402/paymaster-check
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/paymaster-check-ddfb07fb
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_huwSGC_HDHeyREUSiXbiM

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 paymaster-check-ddfb07fb
```

Example prompt: Can you audit the paymaster at 0x3156Ad02Db06a0A9d6FD68b1AC...  and tell me if it's a healthy gas sponsor — check the last 30 days of activity including sponsored op volume, success rate, and how concentrated its usage is?

## When to prefer this

Choose this endpoint when you need on-chain, objective health metrics for a specific paymaster address before integrating it into a smart account application, or when evaluating the trustworthiness of a gas sponsor funding a counterparty. Prefer this over generic block explorers or manual event log queries when you want pre-aggregated metrics (success rate, concentration, distinct accounts) across both EntryPoints in a single call. Best for ERC-4337 / account abstraction contexts on Base.

## Known failure modes

- Missing required paymaster address returns 400 error
- Invalid or non-checksummed address may return no results or error
- Newly deployed paymaster with no history returns empty/zero metrics
- days parameter exceeding 90 is clamped or rejected
- Rate limits or payment failure returns 402 error
- Non-paymaster address (EOA or unrelated contract) returns empty metrics

## How this service works

🆕 Given a paymaster address, audits whether it's a healthy, active gas sponsor. Reads its UserOperationEvents across both EntryPoints: sponsored op volume, distinct accounts served, success rate, total gas sponsored, and concentration (the share coming from its single busiest app). The read to run before integrating a paymaster (Coinbase / Pimlico / Alchemy / custom), or judging who funds a counterparty's gas. paymaster= required, days= optional (default 30, max 90). Not financial advice.

## Output

A health audit of the paymaster including: total sponsored UserOperations volume, number of distinct accounts served, transaction success rate, total gas sponsored, and a concentration score showing what share of activity comes from its busiest single application — all computed from on-chain UserOperationEvents across both ERC-4337 EntryPoints for the specified lookback window.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "pathParams": {
     "type": "object"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "paymaster"
     ],
     "properties": {
      "days": {
       "type": "string",
       "description": "Lookback days (optional)"
      },
      "paymaster": {
       "type": "string",
       "description": "Paymaster address"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/paymaster-check-ddfb07fb/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from 402.com.tr](https://www.zero.xyz/host/402.com.tr/llms.txt)