Client Library
Color Theme Compliance (Beta)
UI Functions

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Power-Up Capabilities are the mechanism through which a Power-Up lets the Trello client know that it would like to add some sort of widget to Trello, when the context is appropriate. Capabilities are the starting point for all Power-Ups' back-and-forth conversation with Trello.

Power-Up capabilities are enabled via the Power-Up Admin Portal ([]). When a Power-Up has enabled a capability, it is expected to include a key for each capability when calling TrelloPowerUp.initialize() from its connectorUrl. The value for each key should be a function that returns the expected payload as documented per each capability.

For instance, to make use of the board-buttons capability, we'd enable it in the Power-Up admin portal, and then add the following to our connectorUrl's javascript:

  'board-buttons': function (t, opts) {
    return [{
      icon: {
        dark: WHITE_ICON,
        light: BLACK_ICON
      text: 'Callback',
      callback: onBtnClick,


When the Trello client goes to render a board view, it knows that board-buttons will need to be drawn if there are any, so it checks all of the Power-Ups enabled on the board to see if any of them have the board-buttons declared. For those that do, it calls the function returned from the connectorUrl and uses the response to render the appropriate additional UI.

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