Why Domyn?
Throughout my fitness journey, I've tested countless workout applications and found them frustrating to use. Most were overly complicated, forcing me into workouts I didn't want to do. They had intrusive advertisements and poor design that completely ruined the experience. When basic functionality was locked behind paywalls, I ended up just using my notes app to track progress. I built Domyn to solve these problems - giving users complete control over their workouts without the BS.
Overview
Domyn is a comprehensive workout application built from the ground up as a solo software engineering project. It empowers users to create fully customized workout routines with complete autonomy over their fitness journey, featuring an elegant and intuitive user interface designed for seamless user experience.
Technical Highlights
Large-Scale Architecture (73,768+ LOC): Modular codebase with 37+ directories including services/, hooks/, utils/, components/, and types/ with 100% TypeScript implementation.
React Native & Expo Stack: Built with React Native 0.79.2, Expo SDK 53, React 19, and Expo Router 5.0 for file-based navigation with typed routes.
Firebase Backend Integration: Complex data modeling with 15+ specialized services, real-time synchronization, and reference-based architecture eliminating data duplication.
Performance Optimization: Custom hook architecture with 50+ specialized hooks, React.useMemo/useCallback throughout, and O(1) exercise history tracking.
Advanced Data Management: Multi-layer caching with EnhancedCacheManager, automatic PR detection across 3 exercise types, and optimistic updates for real-time workout tracking.
Production-Ready Features: Comprehensive error handling with ServiceError system, type-safe constants preventing runtime errors, and Jest testing infrastructure.
Features
Complete Customizability: Users have full control over every aspect of their workout routines.
Intuitive Design: Clean, modern interface that prioritizes user experience and accessibility.
User Autonomy: No restrictions or predefined limitations - build workouts exactly how you want.
Development Journey
Developed entirely as a solo project, showcasing full-stack mobile development capabilities.
Focus on delivering a premium user experience with powerful customization features.
Demonstrates proficiency in UI/UX design, software architecture, and mobile development.