No, parking at Efteling is not free. There are various parking spaces around the park where you can park for a fee. You can choose from a regular parking rate or a premium parking rate, where you can park closer to the park.
It is advisable to buy a parking ticket online in advance, so that you are sure of a parking space and are also cheaper. In addition, there are shuttle buses available during busy days that take you from the parking space to the entrance to the park.