# ABA Routing Number Checksum Validator

> ABA Routing Number Checksum Validator is a paid API for AI agents from checkdigit.openverbs.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-09-14).

Validates a 9-digit US ABA bank routing number using the weighted (3,7,1) mod-10 checksum algorithm

## Facts

- Endpoint: POST https://checkdigit.openverbs.com/v1/routing
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/aba-routing-number-checksum-validator-129fe232
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_XH-fanKXoXj7IZ-oywWA7

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 aba-routing-number-checksum-validator-129fe232 -d '<json body>'
```

Example prompt: Can you check whether the routing number 021000021 is a valid ABA bank routing number using the weighted checksum?

## When to prefer this

Use this endpoint when you need fast, offline-style structural validation of a US ABA routing number before submitting it to a payment system or storing it in a database. It is purpose-built for the ABA (3,7,1) weighted mod-10 algorithm, unlike generic Luhn validators on the same platform which use a different checksum scheme. Prefer it over calling a full bank lookup API when you only need to confirm the number is structurally plausible, not that the bank actually exists.

## Known failure modes

- Routing number fails checksum — returned as invalid result, not an error
- Input shorter than 9 digits after stripping spaces/hyphens — may return validation error
- Input longer than 32 characters — rejected by schema
- Non-numeric characters other than spaces/hyphens — likely validation failure
- Network or payment failure — HTTP 402 or 5xx response

## How this service works

Validate a 9-digit US ABA bank routing number by its weighted (3,7,1) mod-10 checksum. Spaces and hyphens are ignored.

## Output

A validation result indicating whether the supplied routing number passes the ABA weighted (3,7,1) mod-10 checksum, effectively confirming whether it is structurally valid as a US bank routing number

## Request schema (JSON Schema)

```json
{
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "type": "object",
 "properties": {
  "input": {
   "type": "object",
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "type": "string",
     "enum": [
      "POST"
     ]
    },
    "bodyType": {
     "type": "string",
     "enum": [
      "json",
      "form-data",
      "text"
     ]
    },
    "body": {
     "type": "object",
     "properties": {
      "routingNumber": {
       "type": "string",
       "minLength": 1,
       "maxLength": 32,
       "description": "9-digit ABA routing number (spaces/hyphens allowed)."
      }
     },
     "required": [
      "routingNumber"
     ],
     "additionalProperties": false
    }
   },
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "additionalProperties": false
  }
 },
 "required": [
  "input"
 ]
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/aba-routing-number-checksum-validator-129fe232/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from checkdigit.openverbs.com](https://www.zero.xyz/host/checkdigit.openverbs.com/llms.txt)