Vikunja is a free, open-source, self-hostable task management server — a powerful personal and team task manager that can be deployed on your own infrastructure for complete data control. Launched in 2018, Vikunja offers lists, kanban boards, Gantt charts, subtasks, labels, due dates, and team sharing in a clean, modern interface. For privacy-conscious individuals and organizations unwilling to trust task data to third-party cloud providers, Vikunja offers a genuinely capable alternative to commercial task apps with zero subscription fees.

Reference:

Vikunja on Wikipedia

https://vikunja.io