GTDNext Alternatives for Linux

Task Coach is a free and open-source personal task manager designed to handle compound tasks and notes. It's a versatile tool for organizing your to-do list with support for subtasks, categories, and tracking time spent on tasks, making it suitable for both simple task management and more complex project organization.

fluxday is a free and open-source task and productivity management solution designed specifically for growing startups, focusing on streamlined task workflows and team accountability.

GeeTeeDee is a powerful, yet lightweight and portable task management application designed to help users implement the 'Getting Things Done' methodology. It offers a unique blend of hierarchical organization, visual tools, and robust synchronization options, enabling efficient task tracking and productivity across various devices, even offline. Its focus on privacy and user control makes it a standout choice for personal and professional task management.

Germ.io is a collaborative idea management and project planning tool that helps teams capture, refine, and transform initial concepts into structured and actionable project plans.