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Mobile Microfrontends With Zephyr Cloud and Re.Pack

Jan 29, 2025· 51 min· 890 views·Watch on YouTube

Speakers

Zach Chapple, co-founder and CEO of Zephyr, and Jakub Romanik, Re.Pack maintainer at Callstack, discuss mobile microfrontends with host Callstack on React Universe On Air.

When microfrontends help

Zach describes microfrontends as a way to break a frontend into parts that teams can release independently. He suggests considering them when different parts of a platform need to move at different speeds, or when growing teams need to ship faster. Module Federation provides a common way to expose and consume those parts across bundlers.

Bringing federation to mobile

Jakub distinguishes build-time microfrontends, assembled from npm packages, from runtime microfrontends using Module Federation. He says Re.Pack’s earlier integration faced slow builds and configuration hurdles. Rspack and Module Federation 2 features, including runtime plugins and lifecycle hooks, have made the approach more practical to explore for production React Native apps.

Mobile trade-offs and releases

The guests describe lazy loading as a way to keep the initial app bundle smaller and download modules when needed; unused files may also be ejected later. Mobile adds version compatibility work because users keep older shell apps installed, and JavaScript updates cannot replace native binaries or native modules. Zach says teams need to align remote modules with supported app versions.

Zephyr’s role in deployment

Zach and Jakub recount a demonstration that combined Re.Pack, Module Federation, and Zephyr for mobile updates. They shipped a bug and rolled back to a working version in under a minute for the user. Zach says Zephyr coordinates publishing through the existing build pipeline and supports bringing code to a company’s own cloud; teams can reserve over-the-air updates for suitable modules while keeping their App Store release process.

Re.Pack 5 and the closing advice

Jakub says Re.Pack 5 is adding Rspack and Module Federation 2 support, with a stable release still being finalized at the time of recording. He reports cold development builds around five times faster in some apps and HMR falling from about 700 milliseconds to 100 or less, depending on setup. Zach advises teams to examine how they work and ship code, while Jakub encourages interested developers to try the release candidate.

Takeaways

  • Consider microfrontends when parts of the product need independent release cycles or move at different speeds.
  • For mobile federation, plan compatibility between remote JavaScript modules and the native binaries in each shell version.
  • Use lazy loading and remote ejection selectively to manage what users download and retain.
  • Keep App Store releases for native changes; use over-the-air updates only for compatible JavaScript changes and modules suited to that release path.
  • Evaluate Re.Pack 5’s Rspack support against your build and HMR needs; reported speedups vary by setup.

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Mobile Microfrontends With Zephyr Cloud and Re.Pack, Zach Chapple, Jakub Romanik · WhoBuilt