Trello is one of the most popular productivity tools and boasts of a user base of over 1 million teams. Trello is a simple application which makes use of cards, boards and lists, all supported by the 'get things done' idea. Trello integration for Slack reinforces collaboration prowess of Slack and Trello. Teams can directly add cards to boards, add teammates to a specific board and display the details of a board via Slack.