Wikibooks
Wikibooks is a Wikimedia Foundation project that hosts free, collaboratively written textbooks and manuals, organised into books that are broken down into chapters and pages by subject. It launched in 2003 and runs as separate language editions: the English edition holds roughly 98,700 content pages and nearly 297,000 pages in total, and there are around seventy other language editions, eight of them with more than 10,000 pages. It includes two notable sub-projects: Wikijunior, aimed at children and written in age-appropriate, level-banded language, and the Cookbook. Its purpose is instructional rather than encyclopaedic, which makes it distinct from Wikipedia (reference articles) and from Wikiversity (informal lessons, courses and activities) that we also list.
You access it the same way as the other Wikimedia projects. Full database dumps are published at dumps.wikimedia.org as wikitext embedded in XML, refreshed monthly, and there is a MediaWiki API plus a Special Export tool for pulling individual books or pages; any page can also be read as HTML or exported to PDF. For a RAG pipeline the practical route is to strip the wikitext markup and chunk on the existing chapter and section headings, which are already tuned for sequential reading. For an AI tutor the book-and-chapter structure gives ready curriculum sequencing, Wikijunior supplies level-graded content for younger learners, and many volumes carry worked examples and exercises usable as practice items. Coverage and depth vary by title, since volumes are volunteer-written.
The licence position is favourable for builders. Text is dual licensed under Creative Commons Attribution ShareAlike (CC BY-SA 4.0) and the GNU Free Documentation License. Commercial use is permitted, but you must credit the contributors and release any derived text under the same share-alike terms, and embedded images or media may carry different licences, so check before redistributing. Alongside the structured curriculum sources we list (OpenStax, CK-12, Siyavula, Khan Academy) and the standards frameworks (Common Core, NGSS), Wikibooks fills the gap for community-written, subject-organised textbooks across a very wide range of topics and reading levels.
Related sources
Achievement Standards Network
Machine-readable curriculum standards from US states, national bodies and other jurisdictions, modelled as an RDF graph of URI-addressable learning objectives with cross-jurisdiction alignments. Now run by D2L and free to use.
AGIEval
8,062 questions drawn from 20 official standardised exams (SAT, LSAT, GMAT, GRE, Gaokao, AMC/AIME and more) in English and Chinese, packaged as a human-centric benchmark for evaluating foundation models.
CASE Network (1EdTech)
A public registry of machine-readable learning-standard frameworks from all 50 US states and other issuing agencies, run by 1EdTech in the CASE JSON format. The digitally referenceable spine of what to teach, at which level and in what order, rather than the teaching content itself.
CEFR Companion Volume Descriptors
The Council of Europe's 2020 CEFR Companion Volume descriptor set, the de facto international standard for levelling language proficiency from Pre-A1 to C2. A spine of can-do statements for sequencing and grading language teaching.