There is a Magnet boost available in the app (it is located at the top of the sorting tray for puzzle pieces) 

🧲 The Magnet helps join pieces automatically.

🧲 To use the boost, tap it, and a random piece from the tray will be connected to the puzzle on the board.

🧲 The number next to the boost shows how many pieces of it you have.

🧲To get magnets, click on the Magnet icon, and you'll see the available options.