BillionCore is a BIN risk scoring and fraud decision API that evaluates the first six to eight digits of a credit or debit card to assess fraud risk and rebill value. It returns an immediate decision — approve, decline, or review for fraud teams, or force, keep, or avoid for media buyers and affiliate managers — along with the underlying reasons. The API does not handle full card numbers or personally identifiable information, and median decision latency is under one millisecond. Users can obtain an API key within 60 seconds without providing a credit card, and pricing follows a pay-as-you-call model with a configurable spend cap. The tool integrates historical chargeback, refund, and TC40 signals with issuer attributes to generate a single risk score on a scale of 0 to 100. Each lookup provides the score, a decision, and supporting evidence, enabling threshold-based rule creation. The service supports three primary lenses: fraud and payments for blocking risky BINs at checkout while reducing false declines; media buying and arbitrage for identifying high-rebill and high-profit segments; and affiliate agencies for standardizing card quality evaluation across offers, sources, and sub-identifiers. Typical workflows involve sending a GET request containing the BIN and selecting the appropriate lens. The API then returns the live decision, risk score, and reasons. This allows payment teams to approve or decline transactions before a charge occurs, media buyers to allocate budget to traffic with strong recurring-billing history, and affiliate managers to surface fraud-heavy sources early. The service also cross references issuer mismatches and cross border flags. Technical details include a base tier of 15,000 scored lookups per month, with overage charges at 0.012 dollars per call and email support. An additional tier offers 75,000 scored lookups per month. The API refreshes issuer and performance data regularly and requires only the BIN, never the full card number.