Cross-Platform Fitness Progress Tracker

I need a clean, intuitive fitness app whose single, central purpose is progress tracking—no meal plans or workout libraries, just rock-solid data capture and easy-to-read insights. Users must be able to record their weight, log the performance of every workout, and store body-measurement snapshots, then view trends over time through charts and simple stats.

I’d like the same codebase (or tightly aligned builds) deployed to iOS, Android, and a responsive web dashboard so clients can update data from any device. Feel free to recommend React Native, Flutter, or another modern stack that will keep maintenance fast and cost-effective; what matters is a fluid UX, secure cloud sync, and the flexibility to add new metrics later.

Acceptance criteria
• iOS, Android, and web versions released to TestFlight / internal Google Play track / staging URL
• Weight, workout-performance, and body-measurement logging flows fully functional and syncing across devices
• Visual progress reports (line and bar charts) rendering in under two seconds on average mobile hardware
• Basic account system with email or social sign-in and GDPR-compliant data storage
• Brief technical hand-off document and a walkthrough call so I can continue enhancing the product on my end

If you’ve shipped similar data-driven health apps or have strong cross-platform chops, I’d like to see your work and discuss timelines right away.