Timple

Simple Timer App with a couple of quirky features for iPhone, iPad and Apple Watch. And yes, it’s free. Forever. (Menacing glance at other developers)
Settings
- Set work intervals from 5 seconds to 25 minutes (10 minutes for watchOS) or infinite work mode to manually advance to the next round.
- Set rest intervals from 0 seconds to 25 minutes (10 minutes on watchOS).
- Enable or disable the last rest interval.
- Independent sound settings — sound on/off doesn’t mess with your system-wide sound.
- Supports both horizontal and vertical orientations.
- Set a pre-timer countdown for ten, three, or zero seconds.
Timer
- Large digits. Like, REALLY LARGE digits.
- Tmer controls, similar to media navigation.
- Color-supported intervals with clock-like animation.
- Soft, non-irritating sounds generated with a wave-synth on the device. Shoutout to all the 438 Hz fans.
Onscreen Controls
- Rewind to the beginning of the round / double tap to return to the previous round.
- Add 10 seconds to the current round.
- Pause and resume the timer.
- Fast forward 10 seconds.
- Skip to the next round.
IMPORTANT! 
Developer notes about watchOS version: 
- the watchOS version is completely independent, it doesn't synchronize the timer's progress or settings with the parent iOS device. It was technically possible, but it drains Apple Watch battery while application is limited.
- Total session length is limited to one full hour (UI doesn't allow user to set longer than that). And I recommend it for even shorter sessions to save battery. If you need longer sessions with watch sensor data collection, please rely on the Apple Workouts app. It's awesome, too.
Count your intervals and stay healthy, mindful, and happy!