WeKan

Kanban as a method is simple — three columns (todo, doing, done), tasks as cards, dragged between them. Simple enough that paying monthly for it feels wrong, yet Trello's free tier caps boards, automation runs and attachment sizes, and a growing team hits the upgrade prompt.

WeKan is the open-source self-hosted version of that method. 21,025 stars, MIT, and released frequently (currently v10.91). Its goal is direct: put the Trello experience on your own server.

Feature parity is reasonably complete:

• Boards, lists and cards with drag-and-drop.
• Card contents: Markdown descriptions, checklists, due and start dates, labels, members, attachments, comments and activity history.
• Swimlanes: a second horizontal division, by person or priority — something Trello's free tier does not offer.
• Permissions: board administrators, normal members and read-only observers.
• Trello import brings existing boards across with cards and attachments, keeping migration cheap.
• Full localization across many languages.

To be clear about:

• You must deploy it. Official Docker images and a Snap package exist, with MongoDB behind it. Deployment is not difficult, but it is one step more than signing up.
• Visual polish trails commercial products. The features are there, but the styling, animation smoothness and small interaction details do not match Trello — the usual situation with self-hosted alternatives.
• Choosing between this and Vikunja: WeKan is purely kanban, a single format executed thoroughly, suited to teams pushing work through a process. Vikunja is a multi-view task system (list, board, Gantt, calendar), suited to personal tasks plus light project work. If you specifically want a Trello replacement, take WeKan; if you want a personal task hub, take Vikunja.
• It is not a project management platform. No time tracking, resource allocation or reporting — it is a board.

Who it suits: small teams, clubs and families who want Trello's workflow without putting their internal process on someone else's servers.