Interval training, your way. No ads. No paywalls. No nonsense.

CoreInterval is a simple, respectful interval timer. Build workouts, chain circuits, and run them with crystal-clear audio cues—all while listening to your music, podcasts, or audiobooks. Our audio ducking automatically dips your media when cues play, so you never miss a call.

WHY COREINTERVAL?
- Listen to music: Ducking automatically turns down your music so you hear cues clearly, then restores volume
- Full features, always free: No premium tiers, no ads, no artificial limits—everything is unlocked from day one
- Respect for you: No tracking, no enshitification, no forced sign-ups
- Chain workouts together: Build and save reusable circuits that combine multiple workouts
- Custom cues: Use built-in sounds, import audio files, TTS, or record your own voice prompts
- Reliable background runs: Runs smoothly with the screen off; timers stay accurate
- Offline: No internet required; your workouts are yours
- Share your library: Export and import workouts (backup or share between devices)
- Track history: View your completed sessions organized by day
- Beautiful UI: Light and dark themes, including dynamic colors on supported devices

AUDIO DUCKING (ANDROID)
When running a workout while playing music or podcasts, CoreInterval automatically:
- Detects that you're listening
- Gently lowers your media volume
- Plays the interval cue clearly
- Restores your media to full volume

You stay focused on your workout. No missed cues, no awkward silence.

HOW IT WORKS
1. Create intervals and rest periods
2. Add optional audio cues so you know what's coming next, or to give a little motivation
3. Group them into workouts or circuits
4. Hit play, start your music, and go
5. Pause, resume, or skip as needed
6. View your history and plan your next session

PERMISSIONS (ANDROID)
CoreInterval requests:
- Microphone: only if you choose to record a voice cue
- Notifications: to keep the timer visible and reliable
- Foreground service: to ensure timers and cues stay accurate with the screen off
- Battery optimization prompt: optional, to prevent interruptions

No account. Works offline. Respects your time and privacy.