ActivityWatch - Open-source time tracker

Chronoid

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Taim: Automated Time Tracking for Accurate Billing

Timemator for Mac — Automate your time-tracking and forget about the timer. Forever.

Harpoon | Simple time tracking on your Mac desktop

Balance: Mindful time tracking by Alexander Sandberg

Time tracking without being a pain

Rize · Maximize Your Productivity

Tyme

RescueTime: Automatic Time-Tracking Software