Services

DOI Foundation

community

Digital Object Identifier system for persistent identification of scholarly and digital content.

Project Gutenberg

community

Free digital library of 70,000+ public domain books in various formats (EPUB, Kindle, HTML, plain text).

Google Scholar

community

Search engine for scholarly literature — articles, theses, books, abstracts, and court opinions.

Open Library

community

Open, editable library catalog with data for 20M+ books. Part of Internet Archive.

Crossref

community

DOI registration agency providing metadata for 150M+ scholarly works including journals, books, and conferences.

Semantic Scholar

community

AI-powered academic search engine by Allen Institute. 200M+ papers with citation analysis.

arXiv

community

Open-access repository for scholarly articles in physics, mathematics, computer science, and more.

Brilliant

community

Interactive learning platform for math, science, and computer science with visual problems.

Skillshare

community

Online learning community with classes in design, illustration, photography, writing, and business.

Khan Academy

community

Free online education platform with courses in math, science, computing, arts, and test prep.

IGDB

community

Internet Game Database by Twitch. Comprehensive game data with ratings, reviews, and metadata.

RAWG

community

Video game database API with 800,000+ games. Ratings, screenshots, stores, and platform availability.