— data —
Validate IBANs in bulk, without uploading your customer data
3 min read
You have a list of account numbers: a list of donors, a row of debtors, the participants in a direct debit. Before you queue up a batch of payments, you want to know there's no typo in the IBANs. One wrong digit and the payment bounces, or worse, goes to the wrong account.
The IBAN bulk check tool checks a whole list at once. You paste the numbers (or upload a CSV) and get back, per line, whether the IBAN is valid, and for Dutch numbers also which bank it is. Everything happens in your browser; your customer data is sent nowhere.
What the tool does
You paste IBANs (one per line) or upload a CSV and pick the right column. The tool validates each number against the structural requirements of ISO 13616: the length per country code, the allowed characters, and the MOD-97 checksum. For Dutch IBANs it looks up the bank code and shows the bank name. You see a summary (total, valid, invalid) and can download the full result as a CSV.
What the tool does and does not do
It's important to be clear about this. The tool does mathematical validation: is the structure correct, and does the checksum add up? What the tool does not do is check whether the account actually exists, is active, or belongs to the right name holder. That last part requires a paid IBAN-name check at a bank. For spotting typos and invalid numbers in a list this tool is exactly right; for a name-to-account match you need a paid service.
Why "in your browser" weighs heavily here
A list of IBANs is sensitive data. These are the account numbers of your donors, customers or members. You don't want to paste them into some random online checker that logs them or sends them to a server. With this tool the validation happens entirely on your device. Paste 500 IBANs, close the tab, and it's all gone. No copy stays behind at Plainjar.
The pain this removes
- No bouncing payments. You catch typos and invalid IBANs before the batch, not after.
- No one-by-one fiddling. Validating 10,000 numbers takes under a second.
- No privacy risk. Your customer data never leaves your device.
- Usable result. Download the full outcome as a CSV, with a reason per invalid line.
How to use it
- Open IBAN bulk check and paste your list, or upload a CSV and pick the IBAN column.
- Review the summary: how many valid, how many invalid, and per line the bank and any reason.
- Download the result as a CSV to lay alongside your records.
Frequently asked questions
Are my IBANs stored or sent? No. All validation happens in your browser, with no server call and no log. Close the tab and it's all gone.
What exactly does the tool check? The length per country code, the allowed characters and the MOD-97 checksum. For Dutch IBANs the bank code is recognised. Not checked: whether the account exists or belongs to the right name.
Does it work for foreign IBANs? Yes, all SEPA countries and other countries with official IBANs are validated on structure and checksum. The bank-name lookup is for Dutch numbers only.
How many IBANs can I check at once? No artificial limit. The table shows the first 200 for speed; the full list is always in the CSV download.
Check your list: IBAN bulk check. In your browser, and your customer data stays yours.