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API Direct – Substack User Profile Lookup
x402
API Direct – Substack User Profile Lookup is a paid API for AI agents from x402.apidirect.io, paid per call via x402, $0.004/call, status unknown (last checked 2026-10-30).
Retrieves a Substack author's full profile given their handle, numeric user ID, or profile URL.
Price / call$0.004
Success—
StatusUnknown
How this service works
Get a Substack author's full profile by handle, user ID or profile URL.
Output
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.
Example use cases
Research a newsletter creator's background
“I want to know more about the Substack author behind 'natesilver538' — can you fetch their full profile including bio, user ID, and publication info?”
Resolve a Substack URL to author details
“I have this Substack profile URL: https://substack.com/@paulgraham — can you look up the author's full profile from it?”
Enrich a list of newsletter authors
“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?”
Technical details
Endpoint
GEThttps://x402.apidirect.io/v1/substack/user?utm_source=zero.xyzWhen to prefer
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.
Side effects
- 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
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Tags
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