Super Productivity is an open-source (GPL) local-first task management and time tracking app with a built-in Pomodoro timer, time tracking, and Jira integration, storing data locally by default. It is free with no subscription.
Dendron is an open-source hierarchical note-taking tool built on VS Code, with local-first Markdown storage and 100+ commands for managing knowledge bases of tens of thousands of notes. Free and suited to developers and heavy knowledge users.
Anytype is a local-first, offline-capable open-source knowledge management platform featuring end-to-end encryption and an object-relationship model, currently free, ideal for privacy- and data-sovereignty-focused users.