A Trello Power-up is similar to an App, a Plugin or an Addon in other Atlassian applications and are developed by third-parties. Power-ups allow users to add new features to Trello Boards and enhance their functionality in specific areas.

Power-ups are available without the use of Optro - you can take a look at all of the available Power-ups on the Trello Power-up Directory, which contains all publicly available Power-ups.