When using free streaming sites, always ensure your and consider using an Ad-Blocker . Even on legal sites, it makes the experience much smoother by preventing intrusive trackers.
While Vudu is primarily a digital store, their "Free" section is surprisingly deep. They offer thousands of movies with limited commercials.
Pluto TV works a little differently by offering "Live" channels. It feels like flipping through traditional satellite TV, but they also have a robust "On Demand" section.
It’s the most obvious choice, but often overlooked. YouTube has a dedicated "Free to Watch" section under its Movies & TV category.