MIT OpenCourseWare
MIT OpenCourseWare publishes teaching materials from more than 2,500 MIT undergraduate and graduate courses, including lecture notes, assignments, exams, and reading lists. Announced in 2001, it was one of the first large-scale open education projects.
Materials are released under a Creative Commons Attribution-NonCommercial-ShareAlike licence. You can reuse and adapt them for non-commercial purposes as long as you credit MIT and release your derivatives under the same terms. The NonCommercial clause rules the collection out for commercial products.
Content is organised around courses rather than pre-processed for retrieval, so expect to do your own extraction and chunking before it drops into a RAG pipeline.
Related sources
LibreTexts
One of the largest open textbook platforms, covering higher education with some K-12 material. Hosts interlinked textbooks and reference material across science, mathematics, humanities, and social sciences. Mostly NonCommercial, so commercial use is ruled out.
Mason OER Metafinder
A discovery tool that runs a real-time simultaneous search across 21 different sources of open educational materials, rather than searching a static database. Useful for finding content to ingest, not a dataset in itself.
MERLOT
A curated collection of online learning and support materials, plus content-creation tools, led by an international community of educators, learners, and researchers. Points to resources hosted elsewhere across many disciplines.
OER Commons
A digital library of over 500,000 open educational resources gathered from institutions around the world. Aggregates full courses, modules, lesson plans, videos, simulations, and assessments across every discipline and education level.