Kontosjekker

Which bank owns this account number — and is the number even valid?

Kontosjekker answers three questions about Norwegian bank accounts:

1. Which bank owns this account number? The first four digits of every Norwegian account number identify the bank. Kontosjekker maps all 2 300+ of those identifiers to their bank and BIC.
2. Is this account number valid? MOD-11 for domestic numbers, MOD-97 for IBANs, plus conversion between the two.
3. What does the bank look like? Logos, content-addressed and cacheable forever.

The register comes from the Bits BIC/IBAN table, the authoritative Norwegian source. Every response tells you which publication it was answered from.

Try it

curl "https://api.kontosjekker.asamsig.com/v1/accounts/validate?accountNumber=8601%2011%2017947"

{
  "account": {
    "valid": true,
    "bban": "86011117947",
    "formatted": "8601 11 17947",
    "iban": "NO9386011117947",
    "ibanFormatted": "NO93 8601 1117 947",
    "clearingCode": "8601",
    "error": null
  },
  "bank": {
    "bic": "DABANO22",
    "institutionCode": "DABA",
    "name": "Danske Bank",
    "country": "NO",
    "clearingCodes": ["8101", "8102", "…"],
    "logo": {
      "formats": ["png"],
      "hash": "5f2c…",
      "url": "https://api.kontosjekker.asamsig.com/v1/banks/DABANO22/logo.png?v=5f2c…"
    }
  }
}

No key is needed to try it — anonymous callers get 60 requests per minute. See Authentication to raise that.

Where to go next

• Account numbers — what the API checks, and what it cannot
• Authentication — API keys and rate limits
• Logos — serving bank logos
• React component — an account input with bank detection built in
• API reference — every endpoint, generated from the service itself

A validity caveat

A valid check digit means the number is well formed, not that the account exists or that it belongs to whoever claims it. No public register in Norway exposes that. Treat validation as a way to catch typos, never as proof of ownership.