{"uid":"cap_hnpvihHVkgQvmjpQtVLnW","slug":"api-direct-substack-user-profile-lookup-79a4cb17","name":"API Direct – Substack User Profile Lookup","description":"Get a Substack author's full profile by handle, user ID or profile URL.","url":"https://x402.apidirect.io/v1/substack/user?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","HEAD","DELETE"],"type":"string"},"queryParams":{"type":"object","required":[],"properties":{"url":{"type":"string","maxLength":500,"description":"Profile URL, e.g. https://substack.com/@lenny (max 500 characters). Provide one of username, user_id or url."},"user_id":{"type":"string","description":"Numeric Substack user ID, as returned in user_id. Provide one of username, user_id or url."},"username":{"type":"string","maxLength":100,"description":"Substack handle, e.g. lenny, with or without a leading @ (max 100 characters). Provide one of username, user_id or url."}}}},"additionalProperties":false}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.004","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":"$0.004/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.004","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.004","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_QerkN954tU7Z0GPt_ori_","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.004","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Retrieves a Substack author's full profile given their handle, numeric user ID, or profile URL.","exampleAgentPrompt":"Can you pull up the full Substack profile for the author with the handle 'lenny' — I want to see their bio, subscriber info, and any other profile details?","exampleUseCases":[{"title":"Research a newsletter creator's background","prompt":"I want to know more about the Substack author behind 'natesilver538' — can you fetch their full profile including bio, user ID, and publication info?"},{"title":"Resolve a Substack URL to author details","prompt":"I have this Substack profile URL: https://substack.com/@paulgraham — can you look up the author's full profile from it?"},{"title":"Enrich a list of newsletter authors","prompt":"I have a Substack author with user ID 123456 and I need their full profile details — name, bio, and subscriber info — can you fetch that?"}],"resultDescription":"Returns the Substack author's full profile object, which typically includes display name, username/handle, numeric user ID, bio/description, profile photo URL, subscriber count, associated publication(s), join date, and other public profile metadata available on Substack.","failureModes":["Unknown username or handle returns 404 or empty result","Invalid or malformed profile URL returns an error","Numeric user ID not found returns no data","Rate limiting or payment failure returns 402 or 429","Substack profile may be private or deactivated, returning limited data","Ambiguous handle (with or without leading @) may cause lookup inconsistency"],"whenToPreferThis":"Use this endpoint when you need structured profile data for a specific Substack author and you already know their handle, user ID, or profile URL. Prefer this over Substack publication search when you want author-level details rather than publication search results. Ideal for enriching author metadata, resolving identities, or fetching subscriber counts for known creators.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-30T19:07:05.144Z","isFirstParty":false,"canonicalSlug":"api-direct-substack-user-profile-lookup-79a4cb17"}