Trello is a kanban-style visual project-management web application built around boards, lists, and cards, launched in 2011 by Joel Spolsky's New York software studio Fog Creek Software (later spun out as Trello Inc.) and acquired by 📝Atlassian in January 2017 for approximately $425 million.
The product's signature interface — drag-and-drop cards moving across columns that typically represent stages of a workflow — popularized the kanban metaphor far beyond its lean-manufacturing origins and helped establish a generation of consumer-style productivity tools inside enterprise software. Trello extends through Power-Ups (third-party integrations), Butler automation rules, calendar and timeline views, and a generous freemium tier; under Atlassian it has been positioned alongside 📝Jira as a lighter-weight, less-engineering-specific entry point into the Atlassian work-management portfolio.