Should you migrate an existing app?
A rewrite needs a concrete reason: an unsupported dependency, a device feature the current stack cannot handle, or maintenance that prevents needed releases. A newer framework alone is not a reason to replace working software. Compare a targeted repair with a phased migration before choosing a full rewrite.
For a new product, read our React Native and Flutter comparison. This guide focuses on changing an app that already has users.
Audit what must keep working
Inventory sign-in, stored data, deep links, push notifications, subscriptions and device integrations. Record supported devices and operating-system versions. Identify which services and accounts your business controls and which depend on the current supplier.
Test the hardest integration first
Build a small proof of concept around the highest-risk device feature or third-party dependency. Evaluate maintained packages and platform behaviour using the official documentation. Do not estimate a full migration from a polished demo screen alone.
Plan the transition for existing users
Define how authentication and local data survive an upgrade. Agree backwards compatibility for APIs while old and new app versions coexist. Test offline behaviour, permission changes and interrupted upgrades on representative devices.
Release with a recovery plan
Set acceptance criteria for key tasks before implementation. Plan a staged rollout, crash monitoring and support ownership. Store review and user adoption add uncertainty to the release date; account for them in the plan.
What determines the estimate?
Screen count is only part of the scope. Native integrations, data migration, accessibility, device coverage and backend changes can dominate the work. Ask for separate estimates for discovery, the first migrated workflow and the remaining rollout.
What should handover include?
Your business should control its store accounts and receive the agreed source code, build instructions, dependency inventory and operating documentation. Define responsibility for future platform updates and support in the proposal.
React Native documentation and Flutter documentation provide implementation references. Discuss an app migration with the current app, its constraints and the workflow you need to improve.