Wekan is a pretty full featured and FOSS kanban project. The maintainer is very active and there's a good amount of community-submitted improvements.

We use https://www.taiga.io/

You can combine Kanban with scrum if needed.

Edit: and here is the link (https://tree.taiga.io/support/) that gives more information about taiga. It is not apparent from their website that you can host it yourself for free.

look into gitlab, it's become pretty fully featured recently

We have completely replaced a set of jira tools with gitlab. Its great.

I use kanboard. It's much simpler than JIRA, but for pure Kanban it's great. It's open source and you can self host it: https://kanboard.org/ (not affiliated - just a satisfied user)

Trello[1]?

[1]: https://trello.com

I think people are skeptical of atlassian after their cloud migration announcement

Planner in MS Office

It is basic, but has an API and a sort of automation scripting engine and is fully integrated into Teams.

Haven't heard of that but looks very useful and integrated into everything else they do.

If you have office 365 its worth looking at because its included with the subscription. They are going through some internal changes on the planner product, as they are sort of merging it with their "TODO." app with it also.

I'm currently moving my Trello/Kanban stuff in Gitlab. Seems to be going OK so far. And I can make easy add-on via API

Used Trello but it's a bit pricey when it comes to using all of the features. Currently using Restyaboard, which is the free version of Trello, with a Kanban board, Gantt chart, reminders, priorities...etc.

https://kantree.io (they have private-cloud and on-premise options: https://kantree.io/enterprise)

If you have some time check out our app at https://www.paymoapp.com - it's quite versatile (has boards and gantt)