Gutendex vs Urantia Papers

Gutendex is a free, open-source JSON API — built independently of Project Gutenberg — that wraps its roughly 75,000 public-domain ebooks with searchable, paginated metadata: authors, subjects, bookshelves, languages, and direct links to every available download format from plain text to EPUB and Kindle. No account or key is needed to query it, and the project's own source enables cross-origin requests from any domain rather than restricting them. Anyone needing sustained high-volume traffic is asked to run their own instance of the open-source server instead of hammering the public one.

Serves the complete 197-paper Urantia Book as structured JSON — by paper, section, or paragraph — with keyword search (AND/OR/phrase modes) and meaning-based semantic search, plus cross-references to Bible passages and AI-narrated audio for every paragraph. It's built for agent/RAG consumption specifically: a `/toc` endpoint enumerates the whole work up front, and `/paragraphs/:ref/context` returns surrounding paragraphs so a single retrieval call carries enough context. Reading and search endpoints are fully keyless; an optional OAuth app-registration flow exists only for personalized bookmarks and reading-progress, not for basic access.