The two which are MOST likely to have a free virtual charter school in your state are k12 or Connections Academy.

We've been with the latter for eight years. Your state may have something home-brewed all its own, too. Check with the department of education for your state, as some of them have good information about both homeschooling (as in, resources and contact info for local groups) and virtual schooling.

HTH!

Schrödinger's cat walks into a bar. And doesn't.