There are loads of sites on the internet which stream top-rated movies and TV shows for free. Trouble is, it can be hard to know which sites are the best and which offer the most content.
That's where a rather neat system called Reelgood comes in. It collects all those free streams into a single place, from which you can browse and watch.
You'll find the site at https://reelgood.io/browse/movies
However, almost all of the content seems to be restricted to viewers in the USA. So if you're not in the US, or you don't have a way of making your PC appear as though it is, you're probably out of luck on this one.