Is Niagara Falls State Park free to enter?

Yes. You can walk up to the falls overlooks without paying a dime. The park itself is a public space with no admission gate or ticket booth at the entrance, including main viewing areas like Prospect Point, Luna Island, and Terrapin Point. Parking in the official lot costs money, and attractions like Maid of the Mist or Cave of the Winds require separate tickets, but standing at the rail and getting misted is totally free.