IBAN, routing, VAT, EIN
Checksums, offline. A valid IBAN is not a real account, and this says so.
- Runs
- In this tab
- Data sent
- None
- Rounding
- Once, at the end
- Also in
- The Chrome extension
IBAN, routing, VAT, EIN, worked
Showing a worked example — type over it
Result
How the IBAN, routing, VAT, EIN works.
IBAN (mod-97), ABA routing (checksum), EIN, VAT number format by country, ISIN, LEI, credit-card Luhn.
Quoted from the toolbelt spec, the document this tool was built against.
Where these numbers come from.
Negatives are parenthesised because that is what a statement does. The rest is four promises.
Minor units, never floats
Amounts are integers in the currency's smallest unit, end to end. A float never touches a cent.
Rounded once
Rounded once, at the end — never per operand, which is how a split stops summing to the whole.
Unit tested
The arithmetic lives in one unit-tested module, shared without reimplementation with the extension.
No network
There is no request to make. What you type stays in this tab and is gone when you close it.
More in data hygiene
The same number, elsewhere.
A calculator answers the question once. These carry the answer into a product, name what it computed, and argue the method.
- ComponentBankAccountInputRouting + account with checksum validation.
- ComponentVendorMasterBank details versioned, never overwritten.
- ComponentBankDetailChangeAlertThe fraud-prevention surface.
- TermVendorA party we buy from
- TermPayeeThe party receiving a payment
- DocProcure to pay (AP)The complete payables stack: requisition → PO → receipt → bill → approval → payment → reconciliation. AP is where fraud happens and where controls matter most. The design consequence: Every AP screen is a control surface. Approval, segregation of duties, and duplicate detection are not features bolt