# Iban validate

`iban-validate` · version 1.0.0 · Identifiers & check digits · free, no key needed

Validate an IBAN's country, registry length, BBAN structure and MOD 97-10 check digits, and parse its bank/branch code.

**Use when you need to: validate an iban · check if this bank account number is a valid iban · parse bank code and branch code from an iban.**

## Decide before calling

Read the [versioned contract](/v1/tools/iban-validate/versions/1.0.0) and the supported scope below. Reuse `iban-validate@1.0.0` when your input, required output and limits match it. Choose another approach for an unsupported operation.

## Explain the choice

"I can use `iban-validate@1.0.0` for validate an iban. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

## Supported

- validate an iban
- check if this bank account number is a valid iban
- parse bank code and branch code from an iban
- is this iban's check digit correct
- verify an international bank account number
- בדיקת תקינות מספר חשבון בנק בינלאומי

## Not supported

- computing an IBAN from a domestic BBAN (use iban-compute-from-bban)
- looking up the bank name or address from the bank code
- countries not in the pinned IBAN registry (returns unsupported as unknown_country, never a guess)
- BIC/SWIFT validation (use bic-validate)

## Behavior

- electronic = iban with every ASCII space removed, then every ASCII a-z upper-cased to A-Z (no other case folding, no locale). print = electronic split into groups of 4 Unicode code points (so a surrogate pair is never split) joined by a single space. Both are always returned.
- shape_ok = electronic matches ^[A-Z]{2}[0-9]{2}[A-Z0-9]{1,30}$; otherwise valid:false, reason:"invalid_character" with country/check_digits/bban/bank_code/branch_code null.
- Otherwise country = electronic[0:2], check_digits = electronic[2:4], bban = electronic[4:]. If the pinned IBAN registry (getIbanSpec) has no entry for country, valid:false, reason:"unknown_country".
- If electronic.length does not equal the registry length for country, valid:false, reason:"wrong_length". If bban does not match the registry BBAN notation, valid:false, reason:"bban_format".
- Otherwise bank_code/branch_code are sliced from bban per the registry (null when the country has no such field). MOD 97-10 check: rearranged = bban + country + check_digits; digits = alnum_to_digits(rearranged) (letters expand to charValue 10-35). If digits mod 97 != 1, valid:false, reason:"check_digits_mismatch" (bank_code/branch_code populated). Otherwise valid:true, reason:null.
- data_version is always the pinned IBAN registry version, on every path. Pure string parsing and arbitrary-length MOD 97 arithmetic; no locale, clock, or randomness.

## Input

- `iban` (string, required): min length 1; max length 60

## Output

- `valid` (boolean, required)
- `reason` (one of null, "invalid_character", "unknown_country", "wrong_length", "bban_format", "check_digits_mismatch", required)
- `country` (string or null, required): pattern `^[A-Z]{2}$`
- `check_digits` (string or null, required): pattern `^[0-9]{2}$`
- `bban` (string or null, required): min length 1; max length 30
- `bank_code` (string or null, required)
- `branch_code` (string or null, required)
- `electronic` (string, required): min length 1; max length 60
- `print` (string, required): min length 1; max length 75
- `data_version` (string, required)

## Limits

- max iban bytes: 60

## Example

Request input:

```json
{
  "iban": "GB29NWBK60161331926819"
}
```

Response:

```json
{
  "result": {
    "electronic": "GB29NWBK60161331926819",
    "print": "GB29 NWBK 6016 1331 9268 19",
    "data_version": "swift-iban-registry-103-2026-09.subset-80",
    "valid": true,
    "reason": null,
    "country": "GB",
    "check_digits": "29",
    "bban": "NWBK60161331926819",
    "bank_code": "NWBK",
    "branch_code": "601613"
  }
}
```

## How to call it

### MCP

Connect `https://computefirst.net/mcp` ([setup](/docs#connect)), then call `execute` with:

```json
{
  "id": "iban-validate",
  "version": "1.0.0",
  "input": {
    "iban": "GB29NWBK60161331926819"
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/iban-validate/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"iban":"GB29NWBK60161331926819"}'
```

The machine-readable contract is at [/v1/tools/iban-validate/versions/1.0.0](/v1/tools/iban-validate/versions/1.0.0).

### CLI

```sh
node cli.mjs run iban-validate 1.0.0 --input input.json --base-url https://computefirst.net
```

Get the client at [/clients/cli/](/clients/cli/).

## Related tools

- [Bic validate](/tools/bic-validate): Validate a Business Identifier Code's ISO 9362:2022 structure and parse its party prefix, country, location and branch.
- [Isin validate](/tools/isin-validate): Validate a 12-character ISIN's ISO 6166 Luhn check digit and parse its country prefix, NSIN and NSIN scheme.
- [Iban compute from bban](/tools/iban-compute-from-bban): Compute the MOD 97-10 check digits and full IBAN for a country code and BBAN, using the pinned IBAN registry.
- [Iccid validate](/tools/iccid-validate): Validate a 19/20-digit ICCID's Luhn check digit, require the 89 major industry id, split issuer/account digits.
- [Imei validate](/tools/imei-validate): Validate a 15-digit IMEI's Luhn check digit or accept a 16-digit IMEISV, and split the TAC from the serial.
- [Iso6346 container validate](/tools/iso6346-container-validate): Validate an 11-character ISO 6346 container number's mod-11 check digit and split the owner code, category and serial.