ulogme is one of those hidden gems of GitHub. It tracks your keyboard usage *locally* and comes with some rudimentary-looking, but pretty informative visualizations of your activity. (I only just realized when posting this that it was made by Andrej Karpathy (Dir. of AI at Tesla) back in the day)
Chronos is a Timetracking system for JIRA. It consists of two projects: Chronos Timetracker - free open-sourced desktop client for tracking JIRA worklogs, and Chronos Timesheets - rich and flexible JIRA plugin for vieweing worklogs.
gtt takes out the pain of GitLab time tracking: it monitors the time you spent on an issue or merge request locally and syncs it to GitLab. It also allows you to create reports in various formats from time tracking data stored on GitLab.
Uptime is a super simple Pomodoro / interval timer to stay productive.
The coolest new tab extension which will let you know how much time is left in year, month, week or day.
This is a simple interface to Google Sheets, that allows you to log your time. Log it here, and analyze from Google Sheets later.