# Spend Check

> Spend Check is a paid API for AI agents from attester.dev, paid per call via x402, $0.005/call, status unknown (last checked 2026-10-18).

Checks whether a specified spend or payment amount meets defined criteria or thresholds via a verification oracle.

## Facts

- Endpoint: POST https://attester.dev/spend-check?utm_source=zero.xyz
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-18
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/spend-check-44e0c73d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_Ou6kMXptiJWer5WUAnMAI

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 spend-check-44e0c73d -d '<json body>'
```

Example prompt: Can you run a spend check on this transaction to verify whether the amount is within the allowed spending limits before I proceed?

## When to prefer this

Use this endpoint when you need to verify or validate a spend amount against defined criteria before authorizing a payment or transaction. Prefer this over generic payment APIs when you specifically need an attestation-based spend check with cryptographic or oracle-backed verification on the attester.dev platform.

## Known failure modes

- Invalid or missing spend amount returns a validation error
- Malformed request body results in a 400 bad request
- Insufficient USDC balance for the $0.005 call fee causes payment failure
- Spend data outside expected schema format causes rejection
- Network timeout or service unavailability returns a 5xx error

## How this service works

Spend Check: should you pay this counterparty? Watchtower track record, CDP merchant catalog, and address hygiene combined into a clear/caution/avoid verdict with a signed attestation. $0.005 USDC per check.

## Output

Returns a validation result indicating whether the spend passes or fails the check, along with any relevant status or reason codes from the attester.

## Request schema (JSON Schema)

```json
{
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "required": [
      "payTo"
     ],
     "properties": {
      "payTo": {
       "type": "string",
       "description": "0x address or URL of the counterparty"
      },
      "amount_usd": {
       "type": [
        "number",
        "null"
       ],
       "description": "Optional planned payment amount"
      }
     }
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "example"
   ],
   "properties": {
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/spend-check-44e0c73d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from attester.dev](https://www.zero.xyz/host/attester.dev/llms.txt)