Fintech app: Flutter to React Native migration

discovery phase & migration planning

Our senior specialist conducted a full code audit of the product and estimated the complete migration to React Native. The same engineer who performed the estimation later became the tech lead on the project. This became an important factor in staying true to timelines and technical expectations.

full application rewrite in React Native

We rebuilt the mobile application from scratch using React Native, ensuring feature parity while significantly elevating code quality and performance.

The new implementation gave the internal team full visibility and control over the product. It also significantly reduced dependency on a single-tech specialist.

feature expansion & new design implementation

We moved on to expanding functionality and refining the UX. The scope included a multi-step onboarding and KYC flow with backend-driven logic, plus a dashboard with credit score insights, rewards overview, and transaction history.

Among additional features were card management, wallet functionality for linking bank accounts, and advanced transaction filtering.

financial integrations & payment infrastructure

We implemented a complex financial infrastructure by orchestrating multiple systems and services. Stripe processes payment and transaction flows, Plaid secures bank account linking and KYC (Know Your Customer) verification, which ensures bank-grade data security.

Multi-source funding is the core product feature that allows a single transaction to be split across multiple cards. This was achieved through sophisticated transactional logic, which reliably allocates funds between payment sources.

We integrated Marqeta, along with Treasury Prime and Modern Treasury for banking operations and fund movement. All financial flows are managed on the backend, so the client can adjust rules without requiring app resubmission to the App Store.

team scaling & cross-platform development

As the project evolved, our involvement expanded beyond mobile development. We took ownership of QA processes and contributed to the web application development using React.

Additionally, we started migrating the frontend from Rails to Next.js using a Turborepo setup. This architecture enables high code reusability across mobile and web, drastically reducing maintenance overhead and accelerating future feature delivery.

ongoing development

The project continues as an active, long-term collaboration. We keep extending the feature set and supporting the client’s product growth as new requirements emerge.