Be Focused by XWaveSoft - Simple Pomodoro timer in your Mac's menu bar
Timer Tab - Online countdown timer, alarm clock, and stopwatch.
Focusmate - Distraction-free productivity via virtual coworking
Gestimer - For those little reminders during the day
Pomodoro Timer UWP - Be more productive with your time
Online Stopwatch - Online Stopwatch is free to use online tool that allows you to keep track of the important events and tasks that you are performing.