{"uid":"cap_-rEkHzeFW357nmx1AKCNB","slug":"sitecheck-web-intel-unpaywall-open-access-lookup-ad6fdc94","name":"SiteCheck Web Intel – Unpaywall Open-Access Lookup","description":"Unpaywall open-access lookup by DOI (free API; it requires a contact e-mail set in UNPAYWALL_EMAIL, not a key): is the paper open access, OA status, best free full-text link, journal and publisher. Returns metadata and links only, not the PDF.","url":"https://api.webintel-api.workers.dev/api/search/unpaywall?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","required":["doi"],"properties":{"doi":{"type":"string","description":"DOI such as 10.1038/nature12373"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object"}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.002","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.002/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_pFbi4aBzOFRmNEuxPKdBG","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.002","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Looks up open-access status and best free full-text link for a paper by DOI using the Unpaywall API","exampleAgentPrompt":"Can you check whether the paper with DOI 10.1038/nature12373 is available open access, and give me the best free link to read it?","exampleUseCases":[{"title":"Verify open access before paywalling","prompt":"I'm trying to read the paper with DOI 10.1016/j.cell.2021.01.001 — is it available for free somewhere, or do I need institutional access?"},{"title":"Enrich citation list with free links","prompt":"I have a list of DOIs from my literature review. Start with 10.1126/science.abb2507 — is it open access, and what's the direct free full-text URL if one exists?"},{"title":"Check journal OA policy for a paper","prompt":"For the paper DOI 10.1056/NEJMoa2001017, tell me its open access status, which journal published it, and who the publisher is."}],"resultDescription":"Returns metadata about the paper identified by the DOI: whether it is open access, the OA type/status (e.g. gold, green, hybrid), the best available free full-text URL, journal name, and publisher. Does not return the PDF itself, only links and metadata.","failureModes":["DOI not found in Unpaywall database — returns null or empty OA data","Invalid or malformed DOI format causes lookup failure","Paper exists but has no open access version — returns OA status as false with no free link","Upstream Unpaywall API downtime causes request failure","Missing or invalid UNPAYWALL_EMAIL configuration on the server side causes rejection"],"whenToPreferThis":"Use this endpoint when you need to quickly determine whether a specific academic paper (identified by DOI) is freely readable online, and to get the canonical best free full-text URL. Ideal for literature review workflows, citation enrichment, or helping users avoid paywalls. Prefer this over general web search when you have a precise DOI and need structured, reliable OA metadata rather than guessing from search results.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-24T12:45:38.105Z","isFirstParty":false,"canonicalSlug":"sitecheck-web-intel-unpaywall-open-access-lookup-ad6fdc94"}