# How to Vibe Code Your Own Hevy (and Stop Paying for It) > The #1 Workout Tracker & Gym Logger App - Site: https://hevyapp.com - Category: Fitness & Health - Platforms: iOS app, Android app, Web app - Verdict: **Solid side project** (68/100 vibecodeable) - Estimated effort: 3-4 weeks of focused coding ## Verdict Build a focused personal workout tracker and routine planner with React Native and Expo; skip the smartwatch companion and social feed to avoid overwhelming scope. Building a personal-use clone of Hevy's core workout logger and routine planner is a rewarding project, but offline sync and complex relational analytics require patience. While you can build the logging interface and analytics dashboards in a few weekends using Expo and SQLite, handling edge cases in local-first database state reconciliation and building out the social graph takes real engineering effort. Because Hevy Pro costs under $3/month, building this is strictly for learning and personal customization. ### What you can't replicate - The 15+ million active user social network and community graph - Deeply polished native smartwatch companion apps (Apple Watch and WearOS) for phone-free lifting ## What it does Digital workout tracking, routine planning, and social fitness platform for weightlifters to log sets, reps, and weights, monitor PRs, and share routines. ### Core features - Intuitive workout logging interface (sets, reps, weights, warmup/drop/failure tags) - Advanced routine planner with custom split creation - Automatic rest timers with vibration and sound notifications - Personal records (PRs) tracking and 1-Rep Max (1RM) calculations - Advanced exercise progress charts and muscle group distribution heatmaps - Social feed to follow athletes, like/comment on workouts, and copy training routines - Comprehensive exercise library with instructional guides ## The business ### Pricing - Hevy Free: Free — Generous free tier with unlimited routines, basic exercise history, community features, and full workout logging. - Hevy Pro: $2.99/mo — Consumer subscription for advanced analytics, unlimited chart history, and custom exercises. Founded 2019. Team size: ~13 employees. ## The hard parts - Offline-first mobile synchronization with local SQLite persistence and conflict-free multi-device merge upon reconnection - Complex relational schema computing real-time volume, 1RM curves, and progressive overload metrics across large datasets - Real-time social graph infrastructure with activity feeds, comments, and follower permission models ## How to vibe code Hevy ### Prerequisites - Node.js (free): Required for running the React Native / Expo development toolchain. - Expo Account (free): Required for building development builds and managing cross-platform mobile deployments. - GitHub (free): Source control and CI/CD integration. ### Recommended AI tools - Claude Code: Best-in-class multi-file agentic coding tool for scaffolding React Native components, database schemas, and state management logic. - Cursor: Excellent AI code editor for fine-tuning UI layouts, custom chart components, and styling workouts screens. ### Stack - Frontend: React Native with Expo (TypeScript, Expo Router) - Backend: Next.js API routes (or lightweight Node.js/Express server) - Database: Turso (SQLite at the edge) for backend sync + local SQLite (expo-sqlite) for offline-first caching - Auth: better-auth - Payments: None (personal use clone) - Other: Victory Native or Reanimated for workout charts, Zustand for local app state management ### Hosting - Cloudflare (Hosting the companion web app frontend and API endpoints on Workers/D1): $0/mo ### Build guide 1. **Project Scaffolding & Database Schema** — Initialize an Expo project with Expo Router and TypeScript. Define the local and remote SQLite database schemas for exercises, routines, routine_exercises, workouts, workout_sets, and sets metadata (weight, reps, type like warmup/drop/failure). ``` Initialize a new Expo React Native app using TypeScript and Expo Router. Set up a robust folder structure with directories for components, screens, hooks, and services. Create an SQLite database initialization script using `expo-sqlite` that defines tables for `exercises` (id, name, muscle_group, category), `routines` (id, title, notes), `routine_exercises` (routine_id, exercise_id, order), `workouts` (id, start_time, end_time, notes), and `workout_sets` (id, workout_id, exercise_id, set_index, weight, reps, type). Ensure proper foreign keys and indexes are established for high-performance offline queries. ``` 2. **Exercise Library & Custom Exercise Management** — Build the exercise library screen with category filters, muscle group tags, and the ability for users to create custom exercises stored locally and synced remotely. ``` Build an Exercise Library screen in Expo Router that displays a searchable, filterable list of exercises grouped by primary muscle group (Chest, Back, Legs, Shoulders, Arms, Core). Include a modal form allowing users to create custom exercises with name, category, and muscle group fields. Save these entries to the local SQLite database with a sync-pending flag, and render clean badge components for muscle groups using React Native primitives. ``` 3. **Routine Planner** — Implement the routine planning interface where users can group exercises into reusable workout templates with target sets and reps. ``` Create a Routine Planner interface. Allow users to create, edit, and delete named workout routines (e.g., 'Push Day A'). Inside a routine editor view, users should be able to add multiple exercises from the library, reorder them via drag-and-drop or list controls, and pre-define target working sets. Persist routine configurations locally with relational mapping between routines and exercises. ``` 4. **Active Workout Logging Screen** — Build the core active workout session tracker featuring set logging, previous performance reference, set type tags (Warmup, Drop, Failure), and live rest timers. ``` Develop the active workout logging screen. When a user starts a routine, spawn an active workout session tracking elapsed time. For each exercise, render a table of sets where users input weight and reps. Display the user's previous performance for that exercise/set directly above current inputs for progressive overload reference. Add a picker or toggle on each set row for set types: Normal, Warmup, Drop Set, and Failure. Include a floating or sticky rest timer component that triggers automatically upon completing a set, featuring customizable duration presets and audio/vibration feedback. ``` 5. **Progress Analytics & Charts** — Implement exercise history charts, personal records (PR) detection, and estimated 1-Rep Max calculations. ``` Build an exercise progress analytics screen using a React Native charting library (such as Victory Native). For any selected exercise, query historical workout sets to compute and plot max weight lifted over time, total volume per session, and estimated One-Rep Max (1RM) using the Epley formula: `weight * (1 + reps / 30)`. Highlight personal records (PR) clearly on the chart and in exercise history lists. ``` 6. **Backend Sync & Companion Web View** — Set up a lightweight backend API and web frontend companion view to view workout logs and routines on desktop screens. ``` Create a companion web view using Next.js and Tailwind CSS that connects to a shared Turso database via better-auth. Build a clean dashboard displaying historical workout logs, exercise progress graphs, and routine management tools optimized for desktop viewports so users can plan workouts from their computers. ``` ### Cost vs paying **Starting costs (one-time):** - Expo / GitHub accounts: $0 - AI coding credits: $20 - Total: ~$20 one-time **Ongoing costs (monthly):** - Turso & Cloudflare free tier: $0/mo - Total: $0/mo - Paying for the SaaS instead: $2.99/mo - Build time: 45-60 hours - AI tool credits: $20 (one month of Claude Pro / Cursor) - Break-even: Never (paying $2.99/mo for Hevy Pro is far cheaper than valuing your development time) ## Sources - [Hevy Official Website](https://hevyapp.com) - [GetLatka - Hevy Revenue & Team Size Data](https://getlatka.com/companies/hevy) - [App Store & Google Play Store Listings](https://apps.apple.com/app/hevy-gym-tracker-workout-log/id1458813556)