BIN Checker uses the Bitpaysa BIN dataset, which is based on an open BIN list (hopkienne / binlist-data), licensed under Creative Commons Attribution 4.0 International (CC BY 4.0), with Bitpaysa 8-digit overrides and corrections (e.g. 52936051 = Prime Bank PLC, Bangladesh).
This data is not an official IIN register. A BIN describes a range of cards, not a specific card.