BIN 340400 — Lookup & Card Details

BIN 340400 is on the American Express network.

A Bank Identification Number (BIN, or Issuer Identification Number / IIN) is the first 6 to 8 digits of any payment card. It tells the payment network which institution issued the card, what kind of card it is, and where it was issued. The card runs on the American Express network.

American Express cards begin with 34 or 37 and run on Amex's own closed-loop network.

In practice this prefix is what a checkout sees first — risk engines score it, gateways route on it, and merchants use it to decide whether to accept the card class at all. BIN 340400 is institutional data under the ISO/IEC 7812 standard — looking it up reveals the issuing program, nothing about any cardholder.