Free & Open Source

Rigorous Study Notes
Without the Paywall

Free, comprehensive notes for IB, A-Level, GCSE, AP, DSE, university STEM, and programming. Written with undergraduate precision, designed for serious students.

2,000+
Pages
9
Sites
15+
Subjects
100%
Free

Exam Board Notes

University & Programming

Reference & Tools

Why These Notes?

Rigorous & Complete

Every definition is precise, every theorem is proved, every formula derived from first principles. No hand-waving, no shortcuts.

Free & Open Source

AGPLv3 licensed. No fees, no ads, no tracking. Source code available on GitHub for contributions and corrections.

Syllabus-Aligned

Written to official exam specifications. Derivations included. No filler content that won't appear in exams.

Cross-Referenced

Concepts linked across subjects and levels. Search across all sites from any page using Cmd+K.