Free. All of it.

What that includes

• Every lesson, every video and every practice question, with the working shown after each answer.
• Progress kept per learner: what is known, what is fading, and what comes next.
• As many learners as you follow, and access for another adult you choose, like a tutor or a grandparent.
• Your own topics as packs, kept private, shared by email, or exported as a file.
• Printable worksheets, with an answer page for grown-ups.
• The public API, the whole catalog as plain text, and a Markdown twin of every public page.

What we do not do

• No adverts, and never any shown to a child.
• No selling your data, and no passing an email to anyone else.
• No card, no trial that ends, and no paid tier waiting behind the free one.
• No paywall on a lesson once a learner has reached it.

Why it is free

The expensive part of a learning app is usually the marketing, not the teaching. This one is built by a small team without venture money behind it, which means we answer to the people using it rather than to a growth target. The material is written once and read many times, so the cost of one more learner is close to nothing.

If that changes, it will change in the open, and nothing a learner has already earned will be taken behind a wall. The terms say the same thing in the language lawyers prefer.

Using it with a class or a school

Also free, and it works today: one adult account can follow many learners, and access can be shared with the other adults who teach them. If you are setting up for a whole class or a tutoring group and want a hand, or you need a higher limit on the API, write to us and say what you are doing.

For machines

The same answer in a form an agent can parse lives at /pricing.md, and the API reference is on the developer page. There is no quota to buy: the ceiling exists so one runaway client cannot spoil it for everyone.