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API Direct - Substack Post Comments (Nested Thread)
x402
API Direct - Substack Post Comments (Nested Thread) 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 the full nested comment thread for a given Substack post, optionally with AI sentiment analysis.
Price / call$0.004
Success—
StatusUnknown
How this service works
Get the full comment thread of a Substack post, nested.
Output
Returns the full nested comment thread for the specified Substack post, including comment text, author info, reply structure, and timestamps. When sentiment analysis is enabled, each comment also includes Plutchik's Wheel emotion scores, a dominant emotion label, intensity rating, and polarity (positive/negative/neutral).
Example use cases
Audience reaction research for newsletter
“Grab all the comments on this Substack article — https://www.workingtheorys.com/p/product-market-fit — sorted by relevance, and include the sentiment scores so I can see how readers emotionally responded.”
Competitive intelligence on rival publication
“Pull the nested comment thread for this post from Ben Thompson's Stratechery — publication is stratechery, slug is apple-vision — sorted by oldest first, so I can trace how the discussion evolved.”
Community moderation monitoring
“Fetch the full comment thread for post ID 145823901 on Substack, sorted by most recent, so I can quickly review any new replies that need moderation.”
Technical details
Endpoint
GEThttps://x402.apidirect.io/v1/substack/post/comments?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need the full nested comment thread of a Substack post — not just top-level comments — especially when reader discussion depth and reply chains matter. It is ideal for sentiment research, audience analysis, or community monitoring on Substack specifically. Prefer it over generic scraping when you want structured nested data and optional emotion analysis (Plutchik's Wheel) in a single call.
Side effects
- Post URL not found or invalid — returns error with no comment data
- Post has no comments — returns empty thread
- Ambiguous post identifier (missing both post_id and the publication+slug pair) — returns validation error
- Rate limiting or payment failure — returns 402 or 429 status
- Sentiment analysis flag enabled but upstream AI service unavailable — may return partial results or error
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object |
Tags
x402
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