Building a BNPL & Digital Wallet Mobile App at KabCash

Overview

KabCash is a fintech mobile application focused on digital payments, Buy Now Pay Later (BNPL), and virtual card issuance, designed to simplify online purchases and money transfers for users in Latin America.

The app enables users to generate one-time virtual cards, split purchases into bi-weekly installments, manage balances, and send or receive money through a secure, mobile-first experience.

I joined KabCash as a Senior React Native Developer, contributing to the architecture, feature development, and overall quality of the mobile application across iOS and Android platforms.

Key Features

• Virtual Card Generation & Management: Implemented core flows for creating and managing one-time virtual cards used for secure online purchases, ensuring clear UX around card lifecycle, limits, and transaction states.
• Deferred Payments (BNPL) Experience: Built user interfaces that allow customers to split payments into scheduled installments, with transparent breakdowns of amounts, due dates, and repayment status.
• Digital Wallet & Transfers: Developed wallet screens for balance visibility, transaction history, and peer-to-peer transfers using phone numbers or QR codes, focusing on speed and usability.
• Secure Authentication & Sensitive Flows: Integrated secure authentication patterns and guarded flows for high-risk actions such as payments, card issuance, and withdrawals, aligned with fintech security best practices.
• Scalable Mobile Architecture: Helped establish a maintainable React Native architecture with reusable components, predictable state management, and clear separation between UI, domain logic, and API layers.

Collaboration & Process

The project was delivered in close collaboration with a cross-functional startup team, including:

• Product Design (CEO): Translating business vision and user needs into intuitive mobile flows and interaction patterns.
• Project Management & Architecture (CTO & Co-Founder): Aligning technical decisions with roadmap priorities, delivery timelines, and long-term scalability.
• Backend Engineering (Python / Django): Integrating REST APIs for payments, credit logic, user accounts, and transaction processing.
• QA Testing: Supporting test cases, regression testing, and validation of critical payment and edge-case scenarios.
• Marketing: Coordinating feature readiness with launch campaigns and user acquisition initiatives.

We worked in iterative sprints with frequent reviews, ensuring fast feedback loops between product, engineering, and QA.

Technologies Used

• React Native: Core framework for building cross-platform mobile experiences.
• TypeScript: Strong typing for improved reliability and maintainability.
• REST APIs: Integration with backend services for payments, cards, and user data.
• Mobile UX Patterns: Fintech-focused flows emphasizing clarity, trust, and speed.
• State Management & Hooks: Predictable handling of async data, user sessions, and transactional states.

Challenges and Learnings

A key challenge was building financially sensitive user flows where clarity and correctness are critical. Small UX or state-handling issues can directly impact user trust, requiring careful attention to edge cases and error states.

Another important learning was balancing startup velocity with fintech reliability — shipping features quickly while maintaining code quality, security awareness, and long-term maintainability in a regulated domain.

Outcome

The result is a robust and user-friendly mobile application that enables secure digital payments, BNPL functionality, and virtual card usage within a single platform. The React Native architecture supports rapid iteration while remaining scalable as KabCash expands its feature set and user base.