# CUSIP Check Digit Validator

> CUSIP Check Digit Validator is a paid API for AI agents from id-validators.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).

Validates the check digit of a 9-character CUSIP security identifier and splits it into issuer and issue codes.

## Facts

- Endpoint: GET https://id-validators.x402tookit.com/cusip-check?utm_source=zero.xyz
- Price: $0.02/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/cusip-check-digit-validator-5986ac86
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_kJHdQ7e5Ft_FPSw11dWfD

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 cusip-check-digit-validator-5986ac86
```

Example prompt: Can you validate this CUSIP for me — 037833100 — and tell me if the check digit is correct and what the issuer and issue codes are?

## When to prefer this

Use this endpoint when you need to programmatically verify the structural integrity of a CUSIP identifier, particularly when you also need the parsed issuer and issue sub-codes. Prefer this over a generic ISIN or LEI validator when the identifier is specifically a 9-character CUSIP (US/Canadian securities). It is the right choice for pre-trade validation workflows, data ingestion pipelines, and regulatory reporting preparation.

## Known failure modes

- CUSIP is not exactly 9 characters — returns invalid verdict with reasons
- Invalid characters in CUSIP string — returns invalid verdict with reasons
- Check digit mismatch — returns invalid verdict explaining the expected vs actual digit
- Missing required query parameter 'id' — returns an error response
- Service degraded — returns degraded flag true with partial results

## How this service works

Validate a 9-character CUSIP security identifier check digit and split issuer and issue codes.

## Output

Returns a verdict (valid/invalid), the normalised CUSIP string, the isolated check digit, the issuer code, the issue code, a human-readable summary, reasons for any failure, and a source/asOf timestamp. May also include a disclaimer and a degraded flag if the service is operating in a limited capacity.

## 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"
    },
    "queryParams": {
     "type": "object",
     "required": [
      "id"
     ],
     "properties": {
      "id": {
       "type": "string",
       "description": "The CUSIP"
      }
     }
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object",
     "properties": {
      "asOf": {
       "type": [
        "null",
        "string"
       ]
      },
      "issue": {
       "type": [
        "null",
        "string"
       ]
      },
      "issuer": {
       "type": [
        "null",
        "string"
       ]
      },
      "source": {
       "type": [
        "null",
        "string"
       ]
      },
      "reasons": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      },
      "summary": {
       "type": [
        "null",
        "string"
       ]
      },
      "verdict": {
       "type": [
        "null",
        "string"
       ]
      },
      "degraded": {
       "type": [
        "boolean",
        "null"
       ]
      },
      "checkDigit": {
       "type": [
        "null",
        "string"
       ]
      },
      "disclaimer": {
       "type": [
        "null",
        "string"
       ]
      },
      "normalised": {
       "type": [
        "null",
        "string"
       ]
      },
      "notChecked": {
       "type": [
        "array",
        "null"
       ],
       "items": {
        "type": "string"
       }
      }
     }
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/cusip-check-digit-validator-5986ac86/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from id-validators.x402tookit.com](https://www.zero.xyz/host/id-validators.x402tookit.com/llms.txt)