Mobile App

Arc Timer

HIIT timer application covering the full workout lifecycle.

Personal-use project evolved into a production-level application. Full workout flow from setup to execution and tracking.

Key Features

  • Custom workout creation

    Create workouts by defining exercises, intervals and durations.

  • Simple session controls

    Pause, resume, skip, or end a session with minimal interaction during workouts.

  • Session history

    Track completed workouts and review past sessions.

  • Workout import and export

    Share and reuse workouts through file import and export.

  • Multi-language support

    Available in multiple languages for broader accessibility.

Implementation Details

  • State-based timer flow

    Each phase is part of a state machine, enabling controlled transitions and event propagation.

  • 1Hz engine cycle

    Timer engine updates once per second, balancing efficiency with required precision.

  • Reanimated UI-thread animations

    Animations run on the UI thread using Reanimated, avoiding load on the JavaScript thread.

  • File-based workout sharing

    Workouts serialized into files for import, export and reuse across devices.

Tech Stack

  • React Native
  • Expo Router
  • React Reanimated
  • TypeScript