About
An ordered path through technical books whose supporting material is already public, and already scattered.
The problem
A serious textbook often has a surprising amount of free material behind it. The author posts sample chapters. The university publishes the whole course as video. The problem sets and solutions go online. It is genuinely free and genuinely legal.
It is also close to unusable. The lectures are numbered by the course, not the book. Three sections have a sample chapter and the rest do not. The problem sets arrive as one combined file. Working out what to read after section I.7 means searching three sites every time, and most people give up before chapter two.
What this site does
It puts that material back into the book's own order. Every section gets a row with direct links to whatever exists for it, plus, for a growing number of sections, a study guide we write ourselves: what the section is really about, what it sets up later, and where people reliably get stuck.
Tick sections off as you read. The next unread section stays marked, so coming back after a fortnight away takes one glance rather than five minutes of hunting.
How it stays free
There is nothing to fund. The site is static files on a free hosting tier, with no server, no database, and no accounts to run. No advertising, no analytics, no tracking, and nothing for sale. That is not an introductory offer, it is the architecture.
Where your progress lives
In your browser, in localStorage, on the device you are using. It is never transmitted anywhere, because there is nowhere to transmit it to. We cannot see what you have read.
The trade is that progress does not follow you between devices on its own. Every book page has export and import controls that move a small JSON file between devices. That file is also a real backup, worth keeping if you are a long way into a book, since clearing your browser data will otherwise wipe it.
Copyright
We host no copyrighted material and link only to rights holders' own servers. The full position, per-book attribution, and the takedown contact are on the copyright page.
Adding a book
Books are data files, not code. Adding one means writing a single YAML file describing its parts, sections, and free resources; the site builds the pages from it. Contribution instructions are in the repository.
Suggestions are welcome, with one firm rule: a book qualifies only if its supporting material is published free by the author, publisher, or university. We will not link to unauthorised copies.