# IBAN RS Mod-97 Validity Checker

> IBAN RS Mod-97 Validity Checker is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.004/call, status unknown (last checked 2026-10-11).

Validates whether a given IBAN is a mod-97-valid Serbian (RS) IBAN of the required 22-character length

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/check-iban-rs?utm_source=zero.xyz
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/iban-rs-mod-97-validity-checker-36baceff
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_vZMsgbGErU5TxdaQKEHwS

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 iban-rs-mod-97-validity-checker-36baceff -d '<json body>'
```

Example prompt: Can you check whether this Serbian IBAN is valid: RS35105008123123123173 — I need to know if it passes the mod-97 checksum and is the correct 22-character RS format before I send a payment to it.

## When to prefer this

Use this endpoint when you specifically need to validate a Serbian (RS) IBAN using the mod-97 algorithm and ensure it meets the exact 22-character length requirement. Prefer the free sandbox endpoint POST /v1/sandbox/check-iban-rs for testing or non-production validation before incurring the $0.004 USDC per-call fee. Choose this over generic IBAN libraries when you need a hosted, auditable, pay-per-use validation service that handles RS-specific rules.

## Known failure modes

- IBAN too short or too long (not 22 characters) — returns invalid
- Country code is not RS — validation fails
- Mod-97 checksum does not compute to 1 — returns invalid
- Malformed or non-alphanumeric IBAN input — may return error
- Empty or missing value field — request rejected
- Payment of $0.004 USDC not provided — HTTP 402 response blocking the call

## How this service works

Call when an agent needs whether an IBAN is a mod-97-valid RS number of length 22. Send JSON {"value":"RS59AAAA00000000000000"}. Exact $0.004 USDC on Base. Try unpaid POST /v1/sandbox/check-iban-rs first.

## Output

Returns a boolean or structured result indicating whether the provided IBAN is a mod-97-valid Serbian RS IBAN of exactly 22 characters, along with any relevant validation details such as failure reason.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "data": {
   "description": "JSON value for schema-check SKUs. Omit it on string checks such as email or IBAN."
  },
  "value": {
   "type": "string",
   "examples": [
    "RS59AAAA00000000000000"
   ],
   "maxLength": 20000,
   "minLength": 1,
   "description": "Value to check. The route description names the format: email, phone, IBAN, postal code, VAT, national id, or similar."
  },
  "schema": {
   "description": "JSON Schema document for schema-check SKUs. Omit it on string checks."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/iban-rs-mod-97-validity-checker-36baceff/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentshelf.syntexa.ch](https://www.zero.xyz/host/agentshelf.syntexa.ch/llms.txt)