Open study, with optional analytics.
Books, lessons, exercises, the public API and MCP can be used without registering or accepting analytics.
Optional page-view measurement
With your permission, the site loads Google Analytics 4 to count page views and understand which public lessons are used. The tag does not load before you choose “Allow analytics”. Page URLs sent from this site omit query parameters. Google may process browser and device information under its own policies.
Your choice is kept in this browser's local storage. You can change it using “Analytics preferences” in the footer. A new opt-out stops later page views from this browser, though it does not erase data previously processed by Google.
Student progress
Optional account-based progress saving is not currently available. Reading public content does not need a student account.