Shopify spent years on React Native - then rebuilt everything in 12 weeks

Shopify Spent Years on React Native - Then Rebuilt Everything in 12 Weeks

In 2020, Shopify made a bet that resonated across the developer world by writing mobile code once in React Native instead of duplicating every feature in Swift and Kotlin. On Thursday, the company said it’s going back. You read that correctly; the company is ditching cross-platform mobile apps for full native development, and it’s leaning heavily on AI agents to do the heavy lifting.

Agents Replaced Cross-Platform Tradeoffs

The coding agents got a lot better, and by late 2025, Shopify found that an agent could look at how a feature worked on iOS and build the Android version, or do the same thing in reverse. Engineers could also work on platforms they didn’t know particularly well because the agent could handle more of the platform-specific work.

The Rewrite Economics Keep Changing

Shopify isn’t the only company throwing agents at this kind of problem. Bun creator and current Anthropic technical team member, Jarred Sumner used 64 parallel Claude Fable 5 instances to port the JavaScript runtime from Zig to Rust - roughly a million lines of code in 11 days, at an estimated API cost of $165,000. Sumner reported the existing test suite passed across all six supported platforms before the merge.

Zero-Shot Prompting Produced Junk

Shopify first tried giving an LLM the existing React Native code and asking it to rewrite it natively. The results weren’t good. Ali describes the output as slop, but adding more steps didn’t solve the problem. Even when the team had the model write specs and task files before touching the code, it still produced too much code that engineers wouldn’t want to maintain.

Helix Breaks Migrations into Pieces

Enter Helix, Shopify’s internal system for managing the agents doing the rewrite. It takes the migration screen by screen, breaking each one into smaller chunks rather than trying to recreate everything at once. Shopify compares the result with the existing app as it goes, while separate agents look for problems in the code before a human signs off. The system also keeps that review feedback around, so problems caught earlier can inform what happens next.

Codebases Built for Agents

The migration exposed another problem. Agents can change code in seconds, but testing it in a mobile simulator can take twice as long. Shopify worked around that by separating business logic from the UI and letting agents interact with the app through a CLI running on a desktop. Some checks that once took minutes now happen in milliseconds, while the same interface can control a simulator when needed.