Trello is the kanban board that introduced visual task management to the mainstream — organizing work into boards, lists, and cards in a drag-and-drop interface so intuitive that new users understand it within minutes. Created by Fog Creek Software in 2011 and acquired by Atlassian in 2017 for $425 million, Trello's Power-Ups extend it with calendars, automations, and integrations. Its simplicity is its superpower: for teams resistant to complex tooling, Trello removes every barrier between having a task and tracking it.

Reference:

Trello on Wikipedia

https://en.wikipedia.org/wiki/Trello