Building a cross-platform mobile app MVP for 40Love

40Love is a UK-based sports tech startup focused on bringing tennis players, coaches, and organisers onto a single digital platform. The product initially launched as a web-based application built with HTML and CSS, designed using a mobile-first approach. Many users were already accessing the platform through their mobile browsers.

While the mobile-first web experience worked functionally, it had clear limitations. Real-time features such as live leaderboards, instant score updates, and push notifications were either restricted or not possible through the browser. As user adoption grew within the tennis community, the need for a dedicated mobile app became clear.

Exline Labs was engaged to design and build a cross-platform mobile app MVP that could deliver a native mobile experience while supporting the existing product vision.

The challenge was not validating the idea. It was upgrading the experience without slowing momentum.

Key challenges included:

• Moving from a mobile-first web app to a native mobile experience

• Supporting real-time updates for scores, rankings, and tournaments

• Enabling push notifications and in-app payments

• Serving multiple user roles within a single app

• Building an MVP that could scale beyond early adoption

The mobile app needed to feel fast, reliable, and intuitive from day one.

The UX work started by analysing how users interacted with the mobile web version of the product. We identified where browser-based interactions fell short, particularly around navigation, responsiveness, and real-time feedback.

We reviewed comparable sports and tournament apps across app stores, paying close attention to user reviews and common interaction patterns. This helped refine the value proposition of 40Love as a mobile product.

Key UX decisions included:

• Clear separation of flows for players, organisers, and coaches

• Simplified navigation for frequent actions such as match tracking and rankings

• Improved visual clarity for leaderboards and tournament views

• A consistent and familiar interface that reduces learning effort

Clickable prototypes were created to validate flows before development began, allowing refinements early in the process.

The mobile app was built as a cross-platform MVP using Flutter, allowing a single codebase to support both iOS and Android while maintaining a native feel.

Key technical decisions included:

• Frontend: Flutter for consistent performance across platforms

• Backend: Firebase for authentication, Firestore, storage, and real-time data

• Payments: Stripe for secure in-app payments such as tournament fees

• Notifications: Firebase Messaging and OneSignal for push notifications

Firebase was chosen to support live score updates, leaderboard changes, and real-time notifications. The system was designed as a cloud-native platform, enabling fast updates and future scalability as the user base grows.

The result was a cross-platform mobile app MVP that delivered a clear upgrade from the mobile-first web experience.

• Players can register, track rankings, and follow tournaments in real time

• Organisers manage matches, scores, and leaderboards directly from the app

• Coaches gain better visibility and engagement tools

The app provides a smooth, responsive experience on both iOS and Android, supporting real-time interactions, notifications, and in-app payments. It positioned 40Love as a mobile-led platform ready for the next stage of growth.