This is a site as well as two apps, one for videos and one for games. There are no ads and they are completely free. Just make sure to support your local PBS station, which helps fund them.
The videos and games are or/for characters/shows such as Daniel Tiger, Peg and Cat, Cyberchase, Curious George, and many, many more.
I wasn’t aware until I had kids, but most of these shows are produced in Canada and employ lots of comedians. Martin Short is the voice of Cat in the Hat, Gilbert Gottfried and Christopher Lloyd are voices in Cyberchase, etc.
There is a huge amount of content, all of it good.
This is a series run by Jim Henson’s daughter Lisa, who seems to be in charge of at least half of all children’s TV programming these days. You can watch the series for free at PBSKids.com or via the PBS Kids app (also free). Neither the site nor the app has ads either. Just make sure to support your local PBS station.
The show is light-hearted and full of factual information about dinosaurs and prehistoric times (assuming you can ignore the fact that the dinosaurs all speak English, ride in a time-traveling locomotive, and are not constantly trying to eat each other).
There are tons of episodes, available in DVD form. A good bet for any kid who’s really into dinosaurs.