binlist.net is a public web service for looking up credit and debit card metadata.
The first 6 or 8 digits of a payment card number (credit cards, debit cards, etc.) are known as the Issuer Identification Numbers (IIN), previously known as Bank Identification Number (BIN). These identify the institution that issued the card to the card holder.
Requests are throttled at 10 per minute with a burst allowance of 10. If you hit the speed limit the service will return a 429 http status code.