Case Study: Mercari achieves a 60% drop in fraud and chargebacks with Sift

How Mercari fights all fraud and expands its business with one platform

Mercari, a Japan-based mobile peer-to-peer marketplace operating in Japan, the U.S., and the U.K., faced rising payment, promo/referral and spam fraud as it expanded—challenges that overwhelmed a small fraud team and an unsustainable, rules-based manual review process. New, varied attack types in the U.S. made maintaining a safe customer experience difficult without a scalable solution.

Mercari integrated Sift in days and let its machine-learning models learn from live data, rapidly increasing automation (queues in two weeks and confident auto-bans within a month). Within three months chargebacks and fraud dropped by about 60%, and Sift Insights provided real-time reporting that optimized operations and day-to-day decision making.

Mercari

Puneet Shah

Senior Product Manager