You should try Timemator. I don't know about others, but here you can specify certain rules where it should start tracking specific task automatically. For example when VS Code app has been started, it automatically starts task of your choice ("coding" in this example).
You can specify colors to the custom tasks. So I have red tasks for reddit, macrumors, youtube and netflix, which means that was unproductive time. On the other hand, job, school, research are green.
It's also smart. If you forget about stopping the tracking and just leave for a cofee, small talk in the office, etc., after a certain timeframe of inactivity it stops the tracking itself. Very handy!