Free Curricula
Easy Peasy All-in-one Homeschool
Ambleside Online
Connections Academy
K12
MIT Courses
Paid Curricula
Online curriculum
Traditional(using textbooks) curricula
Variety of Courses
Khan Academy (all grades, free)
cK12 Courses (all grades, free)
Open Culture (free)
EDX Courses (free and paid)
Universal Class< (paid)