How a Free Data Catalog Pays for Itself

YJTOON is free: 185 datasets, no signup, no keys, public domain. Running it still costs real money — hosting, domain, and the hours spent curating. Here is the model that keeps it sustainable without paywalling the data.

Free data, paid depth

The catalog answers "what is the fact?" The companion ebook — Open Data for AGI — answers "what should we do about it?" One is a reference, the other is judgment: field guides to open datasets, analysis of data policy, recommendations for action. Charging for synthesis while the facts stay free keeps incentives aligned — the data must remain open, or the book's own thesis collapses.

Why this works

• Message scent: readers arrive from notes like Open Data for AGI: Why It Matters and find the book as a direct continuation, not a detour.
• Zero marginal cost: serving is nearly free — shared hosting with pre-generated static files — so the catalog never needs to convert readers to survive.
• Compounding catalog: every dataset added (browse the catalog) makes both the free tier and the paid companion more valuable.

The takeaway

If you maintain open infrastructure, sell the change your work creates — strategy, curation, judgment — and keep the commons open. That is the arrangement this site runs on.