--- title: Rethinking Payment APIs at Merpay: The Exchange Abstraction description: Merpay's Payment Platform team describes a new abstraction called Exchange to unify fragmented payment APIs. Instead of separate APIs for payments, top-ups,... canonical: https://daily.dev/posts/rethinking-payment-apis-at-merpay-the-exchange-abstraction-qa9c8pgcd twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Rethinking Payment APIs at Merpay: The Exchange Abstraction | daily.dev og:description: Merpay's Payment Platform team describes a new abstraction called Exchange to unify fragmented payment APIs. Instead of separate APIs for payments, top-ups,... og:url: https://daily.dev/posts/rethinking-payment-apis-at-merpay-the-exchange-abstraction-qa9c8pgcd og:image: https://api.daily.dev/og/posts/QA9C8pgcD.png og:image:alt: Rethinking Payment APIs at Merpay: The Exchange Abstraction og:image:width: 1200 og:image:height: 630 og:locale: en --- [Mercari Engineering](https://daily.dev/sources/mercari) [Read post](https://api.daily.dev/r/QA9C8pgcD) # [Rethinking Payment APIs at Merpay: The Exchange Abstraction](https://api.daily.dev/r/QA9C8pgcD "Go to post") Merpay's Payment Platform team describes a new abstraction called Exchange to unify fragmented payment APIs. Instead of separate APIs for payments, top-ups, transfers, and partner settlements, Exchange models any fund movement as a source-to-destination operation with a two-phase Authorize/Capture lifecycle. The design introduces a Value concept to unify payment methods and destinations, passes accounting codes through the API to eliminate hardcoded accounting logic, and uses a Saga pattern for failure compensation in distributed transactions. Extension points (Hooks, Steps, Decisions) allow product teams to inject use-case-specific logic like KYC checks without polluting the core. The goal is to reduce coordination overhead, clarify API responsibilities, and enable faster onboarding of new payment use cases. [#architecture](/tags/architecture "Check all #architecture posts")[#fintech](/tags/fintech "Check all #fintech posts")[#distributed-systems](/tags/distributed-systems "Check all #distributed-systems posts") Aug 06•15m read time•From [engineering.mercari.com](https://api.daily.dev/r/QA9C8pgcD "engineering.mercari.com") [](https://api.daily.dev/r/QA9C8pgcD "Go to post") Table of contents [Background](https://api.daily.dev/r/QA9C8pgcD "Background")[Problems](https://api.daily.dev/r/QA9C8pgcD "Problems")[What is an Exchange?](https://api.daily.dev/r/QA9C8pgcD "What is an Exchange?")[Design Philosophy](https://api.daily.dev/r/QA9C8pgcD "Design Philosophy")[The Anatomy of an Exchange](https://api.daily.dev/r/QA9C8pgcD "The Anatomy of an Exchange")[The Value Concept](https://api.daily.dev/r/QA9C8pgcD "The Value Concept")[Practical Example](https://api.daily.dev/r/QA9C8pgcD "Practical Example")[Future Extensions](https://api.daily.dev/r/QA9C8pgcD "Future Extensions")[Conclusion](https://api.daily.dev/r/QA9C8pgcD "Conclusion") 321 Impressions Comment Bookmark Copy Share your thoughtsPost [](https://daily.dev/sources/mercari) [Mercari Engineering](https://daily.dev/sources/mercari "https://daily.dev/sources/mercari") Mercari's platform is a resource for developers and technology enthusiasts, offering insights into e... 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