Shopify is moving its mobile apps back to Swift and Kotlin, and says AI agents rebuilt the Shop app in 12 weeks

Shopify said on 10 September that it is moving its mobile apps off React Native and back to Swift on iOS and Kotlin on Android. Director of engineering Mustafa Ali wrote that the Shop app, one of the company's largest, went from proof of concept to a fully native release in the app stores in 12 weeks, with a coding-agent system called Helix doing most of the port. The larger Shopify merchant app, which has more than 300 screens, an Apple Watch app, home and lockscreen widgets, and Siri Shortcuts, is underway and will ship later this year.

Shopify adopted React Native in 2020 to stop writing every feature twice, and Ali writes that the framework did what the company needed for years. What changed is that by late 2025 coding agents were good enough to write the second copy of a feature from the first one. "LLMs changed one of the core assumptions behind our 2020 decision," Ali writes.

Helix builds one screen at a time

The team first tried pointing an LLM at the React Native code and asking for a native rewrite. Ali says the output was slop, and adding a specs-first step still produced code the team would not want to maintain. Helix works a checkpoint at a time. A developer points it at a screen; Helix reads the React Native version and proposes an ordered list of small slices. Each slice has to pass tests, match the running app in a visual review, survive two adversarial reviewer agents, and get a person's sign-off before the next slice starts. Feedback from every review is remembered, so the loop needs less supervision as the migration progresses.

The bottleneck was the mobile simulator: an agent can change code in seconds, but running the app in a simulator takes minutes. Shopify separated business logic from the UI so the logic runs headlessly on the desktop, and exposed it to agents through a CLI. Some checks that used to take minutes now take milliseconds, and the simulator only comes in when the agent has to see the screen.

What happens to the shared React Native libraries

Shopify maintains three widely used React Native libraries and says in the same post what happens to each. React Native Skia will keep its Shopify sponsorship through the end of 2026, then William Candillon will fork it under a new name and the original repository will be archived. FlashList, which Shopify says gets around two million downloads a week and has become the default high-performance list for React Native, will keep receiving critical compatibility fixes while Shopify looks for another company to take over long-term stewardship. Restyle has a smaller user base and is being archived, with maintenance ending in late 2026.

The Shop app is done. The Shopify app is next, and Ali writes that Shopify will judge the finished native apps partly by how much of the work agents can eventually handle on their own.

Read Shopify's report alongside a second data point The New Stack cites: Bun creator Jarred Sumner, now at Anthropic, ran 64 parallel Claude Fable 5 instances to port the Bun runtime from Zig to Rust, and reported around a million lines of code in 11 days for an estimated 165,000 dollars in API cost. Each is one company describing its own project. The decision that used to lock a team into one codebase for years is worth re-costing.

Source

Shopify Engineering: Back to native, and The New Stack: Shopify spent years on React Native, then rebuilt everything in 12 weeks.