Trello is project management software offered as a cloud service. The Trello app can be used on iOS and Android devices, and on the web using any major modern browser. It can also be used integrated inside of a Slack client.
The Trello service was launched in 2011. The same year, Wired magazine called it "One of the 7 coolest startups you haven't heard of yet." By 2017, Trello had grown to over 1 million average monthly users, and was purchased by Atlassian for $425 million.
Trello organizes projects visually, in units called "boards." Boards contain lists of items, and each item is represented by a "card." There are many features which allow these components to be customized according to a project's needs. Using a Trello API, organizations can integrate Trello services with other essential project services, such as revision control and cloud storage.