Validating a Fitness App with a Landing Page, Then Building It
A Berlin-based founder validated her fitness app idea with a landing page that collected 2,100 email signups in 10 days, then we built and launched the MVP — all within 5 weeks.
Key Results
The Challenge
Lena, a former personal trainer turned entrepreneur, wanted to build an app that created personalized workout plans based on available equipment and time constraints. She'd seen dozens of fitness apps but none that adapted to real-world limitations — you're traveling, you only have dumbbells, you have 20 minutes between meetings.
She came to us with a detailed PRD, investor interest, and a tight runway. The catch: she needed to prove demand before her seed round closed in 6 weeks.
Our Approach
Phase 1: Landing Page + Validation (Week 1)
Instead of jumping into app development, we recommended validating demand first. We built a conversion-optimized landing page in 4 days:
- Hero section with a clear value proposition and email capture
- Animated demo showing the "workout builder" concept
- Social proof section (Lena's personal training credentials + early tester quotes)
- FAQ addressing common objections
- Mobile-responsive with sub-2-second load times
Lena ran €500 of Instagram ads targeting fitness enthusiasts in Germany and the UK. Results in 10 days:
- 2,100 email signups at a €0.24 cost per lead
- 4.2% landing page conversion rate (industry average for fitness: 2.8%)
- Qualitative feedback from 50 reply-to-welcome-email responses
The numbers gave her (and her investors) confidence to build.
Phase 2: MVP Development (Weeks 2–5)
With validation in hand, we built the core app. Two developers working full-time:
Week 2–3: Core functionality
- Workout generation algorithm (equipment + time + fitness level → personalized plan)
- Exercise library with 150+ movements, each with video thumbnails
- Timer and rest-period tracking during workouts
- User profiles with workout history
Week 4: Social + retention features
- Streak tracking and basic gamification (workout badges)
- Share-to-Instagram story feature (free marketing from users)
- Push notification reminders
Week 5: Polish + launch
- App Store and Google Play submission (via Expo EAS)
- Onboarding flow based on landing page survey responses
- Email sequence to convert waitlist to active users
- Analytics dashboard for Lena to track key metrics
We shipped the React Native app via Expo, which let us publish to both iOS and Android from a single codebase. The Next.js web app served as the marketing site and web fallback.
The Results
First 30 days after launch to the waitlist:
- 680 users activated from the 2,100-person waitlist (32% conversion)
- 34% day-30 retention (fitness app average: 14%)
- 4.6 average workouts per user per week
- 23% of users shared at least one workout to Instagram Stories
The retention numbers were strong enough for Lena to close her seed round at a higher valuation than originally planned.
Key Takeaways
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Validate before you build. The landing page cost €800 (development) + €500 (ads) = €1,300 total. It answered the most important question — "will anyone care?" — in 10 days. Building the full app without validation would have cost 20x that with no guarantee of demand.
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React Native + Expo is the right MVP play for mobile. One codebase, two platforms, over-the-air updates without App Store review. For an MVP, the trade-offs (slightly less native feel) are worth the 50% time savings.
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Retention beats acquisition. Lena's 34% day-30 retention was her strongest investor metric. We spent more time on the workout experience and streak mechanics than on flashy features — and it showed in the numbers.
Technology Stack
“Soatech didn't just build what I asked for — they challenged my assumptions and helped me build the right thing. The landing page idea saved me from spending months on features nobody wanted.”