The classic 25/5 Pomodoro timer
This is the original Pomodoro Technique as designed by Francesco Cirillo: 25 minutes of focused work, followed by a 5 minute break. After four sessions, you earn a longer 15 minute break. It is the most studied and most popular focus interval for a reason — 25 minutes is short enough that starting never feels hard, and long enough to make real progress.
It works especially well for studying, writing, email, and any task you have been procrastinating on. Pick one task, press start, and do nothing else until the bell rings. During the break, stand up and step away from the screen — the break is part of the technique, not a reward you can skip.
Every completed session grows your fruit garden and builds your daily streak, so your focus history is something you can actually see.