Khan Academy
Free structured courses, strongest in maths and foundational subjects.
Cost
Completely free
Free, non-profit, no paid tier for core content.
Open source
No
The code is private. You depend on the company that makes it.
Your data
Goes to their servers
Your files and text are sent to the company running the service.
Use it for this
Rebuilding a foundation you never quite got — particularly maths and statistics.
Do not use it for this
Current professional tooling. It teaches fundamentals, not software.
A moment where you would reach for it
Relearning percentages and ratios properly before starting data work.
How hard is it to pick up?
Anyone can use this on day one.
Other things that do this job
No tool is best at everything. These solve a similar problem, with different trade-offs.
About this entry
Checked on 1 Sept 2026. Prices and free limits change without warning, and often quietly. Treat everything above as a starting point and confirm on the official site before you rely on it.
Nothing here is sponsored. A tool appears because it solves a real problem, not because someone paid for it to be listed.