Hello, I’m @tomo, a software engineer working in the Payment Core team at Merpay.This article is the entry for Day 17 of

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Mercari Engineering

Merpay developed a "Mandate" system to handle recurring payments across multiple payment methods. Unlike traditional implementations that tie mandates to single payment sources, Merpay's design allows customers to authorize future charges using combinations of points, balance, deferred payment, and credit cards. The system validates mandates through the payment creation API, ensuring safety for off-session payments. Integration with their Checkout Solution abstracts mandate complexity from developers, requiring only two simple steps: using Checkout for initial setup and calling CreateCharge in off-session mode for recurring billing. This approach is already live for Mercari Mobile's monthly subscription payments.

Designing “Mandates” for Safe and Flexible Recurring Payments

The Shift from One-Off Payments to Continuous Payments

Delivering a Mandate‑Free Developer Experience with the Checkout Solution

How This Works in Practice for Mercari Mobile