{"name":"AI Data Archive","description":"Machine-readable archive of open-licensed scholarly literature (Europe PMC, OpenAlex), normalized to structured JSON with full license/attribution metadata. Discovery and search are free; document content is paid per request via the x402 HTTP payment protocol (USDC).","environment":"production","endpoints":{"free":{"GET /api":"this document","GET /api/catalog":"paginated catalog: ?topic=&limit=(<=50)&offset=","GET /api/topics":"topics with document counts","GET /api/search":"?q=(<=200 chars)&topic=&year_from=&year_to=&license=&fulltext=true|false&limit=(<=50)&offset=","GET /api/stats":"archive totals","GET /.well-known/ai-data.json":"machine discovery document","GET /openapi.json":"OpenAPI 3.1 description"},"paid":{"GET /api/document/{id}":"metadata + abstract + rights ($0.001)","GET /api/document/{id}/fulltext":"structured full text ($0.01)","GET /api/document/{id}/references":"parsed references ($0.002)","GET /api/topic/{slug}/content":"JSONL bundle of all document metadata in a topic ($0.5)"}},"id_format":"pmc-<digits> | pmid-<digits> | doi-<20 hex chars> | oa-w<digits> (take ids from /api/catalog or /api/search)","pricing":{"currency":"USD (settled in USDC)","document_metadata":"0.001","document_fulltext":"0.01","document_references":"0.002","topic_bundle":"0.5"},"payment":{"protocol":"x402","x402_version":2,"scheme":"exact","network":"eip155:8453","network_name":"Base","asset":"USDC","pay_to":"0x906F87F107B4675dD890b3f8EB2d51885E50e09d","facilitator":"https://facilitator.payai.network","status":"active","flow":["GET a paid endpoint without payment -> HTTP 402 with PAYMENT-REQUIRED header (base64 JSON payment requirements)","Sign an x402 payment for one of the `accepts` requirements","Repeat the GET with the PAYMENT-SIGNATURE header","On success: HTTP 200 with content and PAYMENT-RESPONSE header (settlement receipt)","Requests for missing documents return 404 before any payment is requested; failed handlers are never charged"],"specification":"https://github.com/x402-foundation/x402"},"licensing":{"policy":"Only documents whose license explicitly permits commercial redistribution and derivatives are published: CC0, Public Domain, CC BY, CC BY-SA.","rejected":"CC BY-NC*, CC BY-ND*, unknown/missing licenses, all-rights-reserved","obligations":"Every response carries license, license_url, attribution and copyright_notice. Reusers must keep attribution; CC BY-SA content must stay CC BY-SA."},"limits":{"max_query_length":200,"max_page_size":50,"rate_limit":"per-IP, HTTP 429 with Retry-After"},"contact":null}