Fitness Coaching App
A personal trainer from Lyon had built a loyal following on Instagram and wanted to convert it into a subscription app — but every developer she approached quoted €60K–90K and a 5-month timeline. She had a budget of €22K and wanted to launch before the January fitness season.
Build something similar →The Challenge
A personal trainer from Lyon had built a loyal following on Instagram and wanted to convert it into a subscription app — but every developer she approached quoted €60K–90K and a 5-month timeline. She had a budget of €22K and wanted to launch before the January fitness season.
Our Solution
We chose FlutterFlow for its native animation capabilities, which were essential for the gamified progress UI. Firebase powered real-time sync for the social feed and coach-client messaging. We wrote a custom streak engine as a Dart Cloud Function because no off-the-shelf FlutterFlow component handled the "missed day forgiveness" logic the client needed. RevenueCat managed the paywall and subscription state on both iOS and Android.
Why FlutterFlow for a fitness app
FlutterFlow compiles to native Flutter code, which gives it a significant advantage over web-view wrappers for animation-heavy UIs. The progress ring animations, the streak celebration screen, and the workout timer all run at 60fps without custom Dart — we used FlutterFlow's built-in animation builder. Where we did need custom code (the streak engine, the barcode scanner bridge), FlutterFlow's "Custom Actions" let us write Dart directly and call it like any other action in the flow builder.
Subscription monetisation with RevenueCat
RevenueCat sits between FlutterFlow and the App Store / Play Store billing APIs and normalises receipt validation, entitlement management, and webhook delivery. We configured three tiers — Free, Pro (€9.99/mo), and Coach+ (€24.99/mo). RevenueCat sends purchase events to Firebase Analytics, giving the client a single dashboard showing lifetime value by cohort. The paywall screen was A/B tested directly in RevenueCat: the "social proof" variant (showing subscriber count) converted 34% better than the plain pricing page.
Real-time coach–client messaging
Coaches on the platform can send form check videos, reply to logs, and schedule check-in calls. We used Firestore's real-time listeners for the message feed so coaches see new messages without refreshing. Firebase Storage with signed URLs handled video uploads — the client was concerned about costs, so we added a Dart Cloud Function that re-encodes uploaded videos to 480p before storing them, cutting storage costs by ~60%.
Launch and growth
The app launched on iOS first (Android followed 4 days later). The client promoted it to her 18K Instagram followers and hit 800 downloads on day 1. By the end of month 2, 2,000 users were active weekly, 310 of them on paid tiers — generating €4,200 MRR. Day-7 retention of 68% is significantly above the fitness app category average of ~35%, which the client attributes to the social accountability features.
Features delivered
Technology stack
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Get a free quote →I had three quotes before App Studio — all above €70K and 5+ months. They shipped in 5 weeks inside my budget and the retention numbers speak for themselves.Camille D.Founder, Fitness Coaching App (Lyon)
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