# API Direct – Substack Post Fetcher

> API Direct – Substack Post Fetcher 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).

Retrieve full details of a Substack post by URL, post ID, or publication subdomain and slug, with optional AI sentiment analysis.

## Facts

- Endpoint: GET https://x402.apidirect.io/v1/substack/post?utm_source=zero.xyz
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-30
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/api-direct-substack-post-fetcher-0adaf9fa
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ALILVE3xGzV6VplgVDead

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability api-direct-substack-post-fetcher-0adaf9fa
```

Example prompt: Can you fetch the full content of this Substack post for me: https://www.lennysnewsletter.com/p/all-of-the-lenny-and-friends-summit — and also run sentiment analysis on it so I can see the dominant emotion and polarity?

## When to prefer this

Use this endpoint when you need to retrieve the full content or metadata of a specific Substack post and know its URL, post ID, or publication+slug. Ideal for newsletter monitoring, content research, sentiment analysis pipelines, or aggregating newsletter content. Prefer over general web scrapers when the target is specifically a Substack post, as this endpoint is purpose-built for Substack's structure and supports the optional Plutchik sentiment analysis add-on.

## Known failure modes

- Post not found — invalid URL, slug, or post ID returns a not-found error
- Publication subdomain not found — incorrect or misspelled publication identifier
- Missing required identifier — must provide at least one of: url, post_id, or publication+slug combination
- Paywalled post content may be truncated or inaccessible
- URL exceeds 500 character limit
- Slug exceeds 200 character limit
- Payment failure — insufficient USDC balance for x402 micropayment

## How this service works

Get a Substack post by URL, ID, or publication and slug.

## Output

Returns full Substack post data including title, body content, author, publication metadata, publish date, and post ID. When get_sentiment is true, also returns Plutchik's Wheel emotion scores, the dominant emotion, intensity level, and polarity (positive/negative/neutral).

## Request schema (JSON Schema)

```json
{
 "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": "Post URL, e.g. https://www.lennysnewsletter.com/p/all-of-the-lenny-and-friends-summit (max 500 characters). Provide url, post_id, or publication and slug."
      },
      "slug": {
       "type": "string",
       "maxLength": 200,
       "description": "Post URL slug, e.g. all-of-the-lenny-and-friends-summit, used together with publication."
      },
      "post_id": {
       "type": "string",
       "description": "Numeric post ID, as returned in post_id. Provide url, post_id, or publication and slug."
      },
      "publication": {
       "type": "string",
       "maxLength": 500,
       "description": "Publication subdomain, host or URL, used together with slug."
      },
      "get_sentiment": {
       "type": "boolean",
       "default": false,
       "description": "Set to true to add AI emotion analysis (Plutchik's Wheel) to each result. Adds +$0.001 per request to the cost. Returns emotion scores, dominant emotion, intensity, and polarity."
      }
     }
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/api-direct-substack-post-fetcher-0adaf9fa/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.apidirect.io](https://www.zero.xyz/host/x402.apidirect.io/llms.txt)