Free Switch is a booster in Candy Crush Saga that is introduced in Level 19. It can switch any two candies that do not match, as long as they are adjacent to each other. In the Facebook version, it used to cost a move upon usage, but it no longer does, as of the Sour Salon release.
This booster is now available on iOS and Android as of the Ice Cream Caves update.
The booster will be consumed upon switching any two moveable objects, even if this will cause a valid match.
When switching two special candies, they will not combine but instead switch spots.
Using the free switch on a colour bomb and another (special or normal) candy will not activate the colour bomb, but will instead switch it with the other candy.
A free switch can be used to switch an ingredient with another element. This can be useful in levels where ingredients spawn in columns without exits, and must be moved horizontally. If the ingredient is placed at the exit after using a free switch, it will be collected as well.
Since using a free switch no longer uses up a move after the Sour Salon update on Facebook, you can use this as an extra "+1 move", when in a pinch, although you cannot set off special candy combinations in this way.
In the past, when you used a free switch, bombs would still count down and chocolate would still expand, since the free switch still counted as a move, like shuffling did. These things no longer occur, because the free switch no longer counts as a move.