Behind the Scenes of Developing Mercari’s First Global App, “Mercari Global App”

Hello. I’m @deeeeet from Cross Border (XB) Engineering.

On September 30, 2025, we announced a new strategy for our cross-border business and launched Mercari’s first globally unified app, the “Mercari Global App” (hereinafter referred to as the Global App).
This time, we’re launching a new series that takes you behind the scenes of our global app development projects.
Stay tuned for topics spanning not just backend development, but also mobile development, web development, SRE & Enabling, and much more.

Global App overview 

The Mercari Global App will enable overseas buyers to browse and purchase items from Mercari and Mercari Shops in Japan. The Global App solves problems related to language, payment, and complicated procedures, providing overseas buyers with an easy, safe, and secure shopping experience similar to that of Mercari in Japan.
The Global App will be available in Taiwan and Hong Kong starting from September 30th, 2025, and is planned to gradually expand to more countries and regions in the future.

Publishing schedule

Following is a collection of links to each article. I recommend bookmarking this page for the prompt update, and it will be very useful if you want to check it out at a later date.

Title Author
グローバル展開にむけたアプリと基盤の再構築 @deeeet
グローバル展開を支える基盤の裏側 @yanolab
From Local to Global: Building Seamless B2C Product Integration at Mercari @ahsun
Order management in Mercari Global Marketplace @takady
The Journey of User-Generated Content Translation @aymeric
グローバルWebを支えるSREの裏側 — 開発を加速させるための改善アプローチ @hatappi
Toward a Global Identity Platform @gia
開発者全員が書けるE2Eテスト ─ 普通のgo testで実現するテスト基盤 @ryotarai
グローバルなメルカリの検索バックエンド設計と検索基盤拡充 @shinpei
Building a region‑aware, SEO‑friendly global web app @gary
モジュラモノリスの品質を支えるリーダビリティチーム ― AI時代のスケーラブルなコード管理 @osari.k
How We Deliver Mobile App Updates Faster @manoj
Evolving Mercari’s iOS codebase into a multi-product monorepo @shingt
Enabling internationalization in our web Turbo monorepo @gary
The AI Lied to Me — And That’s When I Learned How to Use It @andrei
Taming Agents in the Mercari Web Monorepo @maxi
BenchMarking Databases For Global APP @amit
Behind the Global Launch: Decoding the Android Engineering Strategy for Our New App @Karthi
Data-fetching strategy for Mercari Global Marketplace Web App @vb
TBD: How we overcome Project management challenges (How to plan a product launch in 6 months) @g-bansal
Guest post from FT payment platform — Engineering for Multi-Currency and Multi-Provider Payments @ryuyama
TBD @manas
TBD: distributed transactions on checkout flow, specially error handling, retry @ahsun
Something about global payment and checkout @huhu
TBD: Ops development with AI @waiting.lau
Sync Saga @Shishir
TBD: High output teams @Atif
TBD: Ordering Features @Shreyasi
TBD @Chong (チョン)
TBD @chris

If any of these articles catch your interest, bookmark this page or follow and check out the official X account for engineers!

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