Music startup — Plaine Images, Lille
Num4
Num4 is a music platform developed in a startup at Plaine Images (Roubaix). I worked in direct collaboration with the founder and CTO on Next.js frontend/backend development, iOS payment integration with RevenueCat, and optimization of an acquisition landing page.
The project story
Making a music offer easier to understand
Num4 needed to explain its offer more clearly and give iOS users a reliable subscription path. The work covered both acquisition and in-app payments.
Working directly with the founder and CTO, I redesigned the interface, developed the Next.js parts and connected the purchase flow to RevenueCat.
The landing page became clearer and iOS payments were integrated into the product flow.
Business Case
Problem
Complete redesign of a music startup's landing page and integration of payments on iOS mobile application.
My Role
UX/UI redesign, Next.js development, iOS payment integration (RevenueCat) and Xcode testing.
Result
Acquisition landing page, Next.js development and iOS payment integration.
Features
Acquisition landing page optimized for conversion
Implementation of i18n for multi-language support (English/French)
iOS payment integration with RevenueCat
Next.js frontend/backend development
Direct collaboration with founder and CTO
Architecture
Implementation of a complex payment tunnel connecting the Apple App Store ecosystem to the Next.js backend via RevenueCat.
RevenueCat Flutter SDK integration for purchase management
App Store Connect configuration (SKUs, Sandbox testers)
Next.js webhooks development for asynchronous validation
Real-time user access rights synchronization
iOS Purchase Integration
From the native in-app purchase to access-rights sync via RevenueCat.