Thousands of hours of coding lessons and certifications.
A complete, project-based curriculum from HTML to data structures, machine learning and interview prep, with free certifications at the end of each track. No upsell, no card.
The best introduction to computer science, free to audit.
Video course · Creative Commons
Maths, science and economics from basics to advanced.
Course platform · Free tier — no card required
Real MIT course materials, openly published.
Course materials · Creative Commons
How valid tests are actually built and validated.
Open textbook · Creative Commons
Free courses, frequency lists and spaced repetition.
App + decks · AGPL / open source
Measurable typing improvement in minutes a day.
Web app · GPL / open source
200+ API docs in one offline-capable app.
Progressive web app · MIT / open source
1,400+ free APIs sorted by category and auth type.
Curated list · MIT / open source
Rebase, stash, bisect and recovery commands on one page.
PDF / web page · Creative Commons
