Cross-Platform Migration
Migrating two separate native apps into one cross-platform codebase is not a lift-and-shift – it is a strategic decision that requires careful planning.
Cross-Platform Migration Without Downtime
We analyse your existing apps, develop a migration strategy that does not disrupt live operations, and carry out the migration incrementally – feature by feature, with clear quality gates.
The essentials of Cross-Platform Migration
- We migrate two separate native apps into one cross-platform codebase – incrementally, feature by feature, with clear quality gates.
- We start with an honest inventory of architecture, dependencies and critical user flows, and only then give a realistic effort estimate.
- Instead of a risky big bang, we migrate feature by feature, keep the app shippable throughout and can stop at any time without endangering operations.
- Characterisation tests lock in the old behaviour and are the net that secures every migration rather than quietly introducing deviations.
- We deliberately use a migration to eliminate selected technical debt without inflating the scope into an open-ended mega-project.
Inventory Analysis
Before a single line of code is migrated, we thoroughly analyse the existing apps: architecture, external dependencies, platform-specific features, technical debt, and critical user flows. This analysis determines which strategy – big bang versus incremental – makes more sense for your app.
Migration Strategy
For most production apps we recommend incremental migration: new features are developed in the cross-platform technology while existing native code is replaced step by step. This minimises risk and enables continuous delivery throughout the migration.
Quality Assurance
Migrated screens are tested on real devices against the original app – visually, functionally, and for performance. We define clear quality gates that ensure the migrated version is at least as good as the original before the next screen is addressed.
Technical Debt
A migration is the opportunity to eliminate technical debt – not carry it into the new technology. We identify poor patterns in the existing code and implement migrated screens with clean architecture that remains maintainable long-term.
Migration process: feature by feature
A cross-platform migration follows not a single cut but a controlled five-phase sequence – keeping the app shippable at every step.
Inventory analysis
Map iOS and Android codebases: clean parts, technical debt, undocumented behaviour.
Migration strategy
Define feature order, make architecture decisions, and prioritise risks.
Characterisation tests
Lock in existing behaviour through tests – the safety net for the entire migration.
Incremental migration
Transfer feature by feature into the cross-platform codebase, app-store-ready after each step.
Quality gates & completion
Behaviour comparison, regression tests, and gradual decommissioning of the old codebases.
Each phase closes with a quality gate before the next one begins.
Big bang vs. incremental migration
Two fundamentally different migration paths – both promise the same goal but carry very different risk profiles.
| Big Bang | Incremental | |
|---|---|---|
| App remains shippable throughout | ||
| Risk concentrated at one moment | ||
| Can stop without disrupting operations | ||
| Early delivery of partial results | ||
| Simple initial planning | ||
| Suitable for production apps |
For production apps with live operations, the incremental path is the safe choice.
What matters for Cross-Platform Migration
What matters first in a cross-platform migration is an honest inventory. Which parts of the existing apps are clean, which are technical debt, and which behaviour is documented at all? Without that picture, every effort estimate is wishful thinking. We analyse first and only then promise, because a migration is never a mere copy job.
Big bang is the wrong way for live apps. Rewriting an app completely and flipping the switch on one cutover date suspends every bit of progress for months and piles the entire risk onto a single moment. We migrate feature by feature, keep the app shippable throughout, and can stop at any time without endangering operations.
The central discipline is preserving behaviour rather than quietly changing it. Otherwise a hundred small deviations creep in during the transfer that look harmless on their own and together break the app. Characterisation tests that lock in the old behaviour are the net that makes a migration safe in the first place.
A migration is also the best chance not to carry old architectural sins along. But that is a deliberate trade-off: what do we improve now because it is being touched anyway, and what do we leave for the time being to keep the scope manageable? Want everything at once and you turn a migration into an open-ended mega-project.
Incremental Migration
Rather than the risky big-bang migration, we recommend an iterative approach for production apps: feature by feature is migrated while the app continues to be developed and deployed continuously.
Eliminate Technical Debt
A migration is the ideal opportunity not to carry poor architecture decisions forward. We migrate with a fresh eye on code quality and long-term maintainability.
Inventory Analysis First
Without a thorough analysis of the existing code, any migration plan is speculative. We analyse first – and then provide a realistic assessment of effort and risks.
Switch without starting over
With us you're always one step ahead technologically and tap directly into our extensive app development expertise. We take a close look at your app idea, identify key success factors and create tailor-made applications. Your visions and goals are at the heart of our joint project work.
Expert knowledge in app technologies
React Native, Flutter, native iOS and Android: we pick the stack to fit your project, not our preference.
Comprehensive user experience know-how
Intuitive operation and seamless interactions decide ratings and how long users stay in the app.
Proven track record
Published apps in the App Store and Play Store, from MVP to mature platform.
Versatile team
Concept, design, development and backend come together in one team that works without interface friction.
Long-term partnerships
We stay after launch and keep evolving your app with maintenance and updates.
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