5 more collections that put their archives online for everyone

These five span Greek mythology sourced from the original ancient texts, a knowledge graph mapping how concepts relate to each other across languages, and a database mapping who in power is connected to whom.

• Theoi Greek Mythology (theoi.com) One of the most comprehensive references to Greek mythology online, with entries for gods, titans, nymphs, creatures, and places built from primary source quotations from Homer, Hesiod, Pindar, Ovid, and dozens of other ancient writers. The site doesn't retell the myths — it assembles them from translated originals, so we can read a wide range of ancient references to a figure like Persephone or Prometheus in one place and see where the sources contradict each other.

• Encyclopedia of World Problems and Human Potential (uia.org) Over 56,000 documented world problems and more than 31,000 proposed solutions, maintained by the Union of International Associations in Brussels. Each problem is cross-referenced with related problems, contributing factors, and the organizations working on them. We can start with deforestation and follow the links through soil erosion, food insecurity, and biodiversity loss, and at each step see which international bodies have proposed responses.

• JECFA Food Additive Database (apps.who.int/food-addit…) The WHO and FAO's Joint Expert Committee publishes its safety evaluations of food additives used worldwide through this searchable database. Each entry includes chemical specifications, acceptable daily intake levels, and the committee's full safety assessment. This is the international regulatory primary source that national food safety agencies reference when setting their own standards.

• LittleSis (littlesis.org/database) A free, crowdsourced database mapping the relationships between powerful people and organizations, primarily in the United States. The name is short for "Little Sister," a play on "Big Brother." We can look up any politician, CEO, or lobbying firm and see a visual map of their connections — who donates to whom, who sits on which boards, who worked where before entering government. All data comes from government filings, news articles, and other public sources.

• ConceptNet (conceptnet.io) An open knowledge graph showing how words and concepts relate to each other across languages. We can type in "library" and see that it's a type of building, that it contains books, that reading happens there, that a librarian works there — then follow any of those connections outward into further relationships. The database is used in natural language processing research and is freely available for anyone to explore.