Tweek

nTask

Project management software that enables your teams to collaborate, plan, analyze, and manage everyday tasks. The essential plan is free forever with 100 MB storage and five users/teams. Unlimited workspaces, meetings, assignments, timesheets, and issue tracking

Taskade

Outline tasks, notes, generated structured lists and mind maps with Taskade AI

Asana

Project management good for distributed teams

Kumu.io

Relationship maps with animation, decorations, filters, clustering, spreadsheet imports, etc. The free tier allows unlimited public projects. Graph size unlimited. Free private projects for students. Sandbox mode is available if you prefer not to leave your file publicly online (upload, edit, download, discard)