Stripe details scaling Radar: fuller training history plus agent-assisted ML cut fraud

emilygsands · x · 2026-10-20

Stripe's full blog post on scaling Radar: the fraud models lean on network-wide signal connections (a new card at one business may have years of trusted history elsewhere on Stripe; an IP links activity across cards). Shield scores payments in milliseconds.

Motivation: despite 800M training transactions, Shield used only a fraction of available history — most payments with no reported fraud were discarded for efficiency. Fuller history should help separate fraud from behavior that's unusual network-wide but normal for a specific card or business.

Costs: a single pass took a day, recent payments had incomplete fraud labels, and more experiments outpaced manual capacity — hence the agent-assisted experiment loop. The winning SWA setup now prevents tens of millions in additional fraud per year.

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