Explorer
Free
Tiers 1–2 · 15 concepts · guided walkthroughs · live visualizations · progress saved on device · Tiers 3–8 locked
Checked 11 Oct 2026
Plans and prices
Principia pricing
Principia Pro
$49.99 a year
8 tiers · 93 concepts
Checked 22 Sep 2026
Principia Pro Monthly
$6.99 a month
All 8 tiers · 93 concepts · guided walkthroughs · printable study aids · future content included · cancel anytime
Checked 11 Oct 2026
Principia Pro Annual
$49.99 a year
All 8 tiers · 93 concepts · guided walkthroughs · printable study aids · future content included · 7-day free trial
Checked 11 Oct 2026