Sale has ended but you can still get this app.
Download Focus in flow Pro: pomodoro timer(No Ad) Now

Official Description

"Focus in flow" is a time-management app to help you get the task done as efficiently as possible. Base on pomodoro technique, you can make good habit of working and learning intently. The nature sounds can stay you in peace and enter you in flow.

Features:
1. Base on Pomodoro Technique:25-minutes fully concentrated periods, separated by 5-minutes short breaks
2. Allows customizing the length of focuses and breaks
3. Five natural sounds: ocean, forest, rain, meditation and night
4. Tap the Timer Circle to turn ON/OFF the natural sounds
5. Track your task by day, by week and by month: help you to make good habit