Beast Academy
Would recommend
I have two kids in Beast Academy in their free time (they attend K and 1) and have been a subscriber for 2 years. Beast Academy has a ton of content and is very well done. There are ~150 lessons per grade level, grades 1 - 5. Each lesson has an accompanying video (~2-4 minutes, also well done), and there are many extension lessons for those that to go beyond the basics as well. It is well tuned for difficulty -- requires a decent amount of mastery to get through, but scales up in challenge for kids who can take it. My main complaint is that I think it follows the standard math curriculum closely and using "modern" teaching methods for arithmetic where they drill a dozen different ways of adding numbers depending on if it will wrap, large and small, etc instead of the one true way that I learned (add to 10/20, then vertical addition, then you're done). So that feels like lesson bloat and I think the kids got a bit bored of it after spending ~100 hours each. If you're looking for a K-5 homeschool math that is comprehensive and which kids can do independently, I don't think you can do better than this. Good preparation for Math Academy