Kanri Is a Free, Offline Alternative to Trello
This streamlined kanban app lets you drag cards from one column to another.

If you like the Kanban method but have grown tired of using bloated, online-only tools, Kanri is a free open-source alternative you can install on Linux, macOS, and Windows that works entirely offline. It even supports importing from Trello.
We've recommended the Kanban method, and related tools, for tracking your work and visualizing projects. And there's nothing about Kanban that needs to be digital—it works well with sticky notes on a wall or even a notepad. Most people, however, depend on apps like Trello for the job—but Trello has a few limitations. There's no offline mode on the computer, for one thing, and the app has a habit of asking you to upgrade. If you'd prefer something simpler that works offline, Kanri might be what you're looking for.
To get started, simply download the application and open it. There's no need to create an account—you can just start using the application. You can make new boards and start adding cards. Click a card to view more details.

You can add a description, due date, tasks, and tags—that's it. There's no attachments or collaboration features, which is going to be a downside for some. There's also no cloud storage or syncing—everything lives on your local device. It is possible to export your board when it comes time to replace your computer; still, the lack of syncing means this application won't work for everyone.
On the other hand, if all you want is a quick Kanban application you can use on your computer, Kanri is just about perfect. It's fast and works without an internet connection, and there are no limits to the number of boards or cards you can add.
There are a few nice touches, too. You can set custom backgrounds for all of your boards, making it easy to tell them apart at a glance while also making things a bit more fun. And there's support in the settings for customizing the color scheme.
And another big feature is the ability to grab existing boards from Trello. You can import all of your Trello boards at once or any individual board—whatever you prefer. All columns and cards are grabbed, including the description, due dates, and any sub-tasks. What doesn't come along are attachments and activities, mostly because Kanri doesn't support those features.
Even so, I bet Kanri supports most of what people use more feature-rich (and expensive) Kanban applications for. Give it a shot if you're looking for something simpler.