A velocity rule is a rolling-window counter – for example, more than five attempts on the same card in the last hour. Specter maintains these counters per card, per device IP, per device fingerprint, and per customer, so you can catch bursts that a single transaction wouldn't reveal.

Velocity checks are evaluated in-process as local rules, so they add minimal latency and carry no per-decision fee. They are also fail-open: if the counter store is unavailable, the check never blocks a genuine customer.

→ See velocity rules in the rule engine