> **For coding agents and LLMs:** This is one page from the Social Fetch docs (markdown export). For curated orientation and workflow guidance, start with [`/llms.txt`](https://www.socialfetch.dev/llms.txt); for agent onboarding and crawl rules, use [`/agents.txt`](https://www.socialfetch.dev/agents.txt); for the full endpoint list with links to pages like this one, use [`/llms-endpoints.txt`](https://www.socialfetch.dev/llms-endpoints.txt); for one platform's parameters and curls, use [`/llms-{platform}.txt`](https://www.socialfetch.dev/llms-tiktok.txt); use [`/llms.json`](https://www.socialfetch.dev/llms.json) when you need structured JSON for tool registration.

## This page

- **On-site (HTML):** <https://www.socialfetch.dev/docs/api/v1/substack/publications/publication/posts/search/get>
- **Markdown (.mdx) URL:** <https://www.socialfetch.dev/docs/api/v1/substack/publications/publication/posts/search/get.mdx>

## API base URL and authentication

- **API origin (from OpenAPI `servers`):** `https://api.socialfetch.dev`
- **Authentication:** send `x-api-key: sfk_...` on `/v1/**` and `/v2/**` routes unless the operation is explicitly anonymous (check OpenAPI `security`, the [API reference hub](https://www.socialfetch.dev/docs/api.mdx), [`/llms.txt`](https://www.socialfetch.dev/llms.txt), or [`/llms.json`](https://www.socialfetch.dev/llms.json) for each route).
- **OpenAPI JSON:** <https://www.socialfetch.dev/openapi.json>

## Recommended docs entrypoints (this site)

- [Documentation overview](https://www.socialfetch.dev/docs.mdx) — top-level orientation (markdown).
- [Quickstart](https://www.socialfetch.dev/docs/quickstart.mdx) — authenticate with `x-api-key`, validate auth with `whoami`, and understand the JSON envelope.
- [SDK](https://www.socialfetch.dev/docs/sdk.mdx) — official TypeScript SDK guide, including `SocialFetchClient`, `Result`, and `unwrap()`.
- [Capability matrix](https://www.socialfetch.dev/docs/capability-matrix.mdx) — every operation with identifiers, pagination, outcomes, media download, credits, and its SDK method. Generated from OpenAPI, so use it for route selection instead of scanning individual pages.
- [Recipes](https://www.socialfetch.dev/docs/recipes.mdx) — copyable workflows (brand monitoring, transcripts, Ad Library, creator scoring, Reddit research) with credit callouts and SDK examples.
- [Integrations](https://www.socialfetch.dev/docs/integrations.mdx) — MCP for AI clients, n8n verified node, Apify Store Actors, Make custom app, SDK, and REST API connection paths.
- [MCP product page](https://www.socialfetch.dev/mcp) — hosted MCP overview, OAuth, Skills install.
- [MCP integration](https://www.socialfetch.dev/docs/integrations/mcp.mdx) — hosted `/mcp` server, OAuth, Cursor/VS Code/Claude install snippets, 910 endpoint tools, plus docs_search/docs_read for implementation help.
- [n8n integration](https://www.socialfetch.dev/docs/integrations/n8n.mdx) — install `n8n-nodes-socialfetch`, credentials, and workflow examples.
- [Apify integration](https://www.socialfetch.dev/docs/integrations/apify.mdx) — Store Actors under @social-fetch, PPE billing, dataset export, and quick start.
- [Make integration](https://www.socialfetch.dev/docs/integrations/make.mdx) — custom app modules for Make scenarios, API key credentials, and module catalog.
- [`/llms-endpoints.txt`](https://www.socialfetch.dev/llms-endpoints.txt) — every documented operation with a direct link to that route's agent-readable markdown page (prefer this over parsing OpenAPI).
- [`/llms-{platform}.txt`](https://www.socialfetch.dev/llms-tiktok.txt) — per-platform endpoint files generated from OpenAPI (parameters, credits, curls).
- [`/agents.txt`](https://www.socialfetch.dev/agents.txt) — agent crawl/onboarding file with capabilities, auth rules, and allowlist.
- [`/llms.json`](https://www.socialfetch.dev/llms.json) — structured machine-readable operation inventory with parameter names, pagination, outcomes, credits, and SDK mapping.
- [API reference hub](https://www.socialfetch.dev/docs/api.mdx) — human-friendly index of operations with links into generated pages.
- [Errors](https://www.socialfetch.dev/docs/errors.mdx) — shared error envelope and HTTP status guidance.
- [Credits](https://www.socialfetch.dev/docs/credits.mdx) — metering, `402`, and planning batch jobs.
- Outcome semantics such as `found`, `not_found`, and `private` are documented in [Errors](https://www.socialfetch.dev/docs/errors.mdx) and on operation pages when present in the OpenAPI contract.

## Markdown docs convention

- Every docs page has a markdown twin: append **`.mdx`** to the docs pathname (for example `/docs/quickstart` → `/docs/quickstart.mdx`).
- Agents that send `Accept: text/markdown` on `/docs/**` HTML URLs may receive markdown directly (same URL, `Vary: Accept`).
- Published blog posts use the same convention: `/blog/{slug}` → `/blog/{slug}.mdx`, or `Accept: text/markdown` on the HTML URL (`Vary: Accept`).

---
# Search Substack publication posts (https://www.socialfetch.dev/docs/api/v1/substack/publications/publication/posts/search/get)

## Summary

Search the posts inside a Substack publication.

**Tags:** `Substack`

## HTTP

- **Method:** GET
- **Path:** `/v1/substack/publications/{publication}/posts/search`
- **Base URL:** `https://api.socialfetch.dev`

## Capability summary

- **SDK mapping:** `client.substack.searchPublicationPosts({ publication: "astralcodexten", query: "climate" })`
- **Accepted identifiers:** `publication` (path), `query` (query)
- **Pagination:** page via `page`, next page: `data.page.nextPage`, has more: `data.page.hasMore`
- **Business outcome field:** `data.lookupStatus` with values `found`, `not_found`, `restricted`

## Credits

- **Base:** 1 credit per successful lookup.
- **Maximum on success (200):** 1 credit.
- **Failed requests (`lookup_failed`, `503`):** not charged.
- **Authoritative field:** `meta.creditsCharged`.

## Authentication

- **`x-api-key`**: API key (`sfk_...`)

## Parameters

### `publication` (path)

- **Required:** yes
- **Constraints:** type `string`; minLength: 1; maxLength: 400
- **Description:** A publication: its numeric id (`89120`), its Substack subdomain (`astralcodexten`), its host (`www.astralcodexten.com`) or its URL. A numeric id is refused with a 400 on the routes that need a subdomain, host or URL.

### `query` (query)

- **Required:** yes
- **Constraints:** type `string`; minLength: 1; maxLength: 200
- **Description:** Text to search for inside the publication.

### `page` (query)

- **Required:** no
- **Constraints:** type `integer`; default: `0`; minimum: 0; maximum: 20; nullable
- **Description:** Page number, 0 to 20; ten results a page.

## Responses (status codes)

- **200**: Substack search posts.
- **400**: Invalid request
- **401**: Missing or invalid API key
- **402**: Insufficient credits
- **500**: Unexpected or billing error
- **502**: Lookup could not be completed.
- **503**: Service temporarily unavailable; safe to retry with backoff.

## Response body (200)

Substack search posts.

### Field outline

- **data** (required) — type `object`. Endpoint-specific response payload.
  - **lookupStatus** (required) — type `string`; enum: found, not_found, restricted. Whether the publication was found.
  - **restrictedReason** (required) — type `string`; enum: invite_only, flagged, paid, null; nullable. Why the publication is restricted, when it is.
  - **publicationId** (required) — type `integer`; nullable. Numeric publication id.
  - **query** (required) — type `string`. The query that was searched.
  - **results** (required) — type `array`. Matching posts with highlighted snippets.
    - _items:_
      - **post** (required) — type `object`. The matching post.
      - **highlights** (required) — type `array`. The highlighted snippets for the match.
        - _items:_
  - **publications** (required) — type `array`. Publications involved in the results.
    - _items:_
      - **id** (required) — type `integer`. Numeric publication id.
      - **name** (required) — type `string`; nullable. The publication's name.
      - **subdomain** (required) — type `string`; nullable. The publication's Substack subdomain.
      - **customDomain** (required) — type `string`; nullable. The publication's custom domain, when it has one.
      - **apexDomain** (required) — type `string`; nullable. The publication's apex domain, when it has one.
      - **url** (required) — type `string`; nullable. The publication's canonical base URL.
      - **host** (required) — type `string`; nullable. The host its pages are served from.
      - **description** (required) — type `string`; nullable. The publication's description.
      - **language** (required) — type `string`; nullable. The publication's language code.
      - **kind** (required) — type `string`; nullable. `newsletter`, `podcast` or Substack's own type.
      - **createdAt** (required) — type `string`; nullable. ISO 8601 timestamp, or null when Substack does not publish one.
      - **firstPostAt** (required) — type `string`; nullable. ISO 8601 timestamp, or null when Substack does not publish one.
      - **hasPosts** (required) — type `boolean`; nullable. Whether the publication has posts.
      - **isExplicit** (required) — type `boolean`; nullable. Whether the publication is marked explicit.
      - **isInviteOnly** (required) — type `boolean`; nullable. Whether the publication is invite-only.
      - **isFlagged** (required) — type `boolean`; nullable. Whether the publication is flagged.
      - **noIndex** (required) — type `boolean`; nullable. Whether search engines are asked not to index it.
      - **isOnSubstack** (required) — type `boolean`; nullable. Whether the publication is hosted by Substack.
      - **commentsEnabled** (required) — type `boolean`; nullable. Whether comments are enabled.
      - **notesEnabled** (required) — type `boolean`; nullable. Whether Notes are enabled.
      - **defaultCommentSort** (required) — type `string`; nullable. The default comment order.
      - **annualDisabled** (required) — type `boolean`; nullable. Whether annual plans are disabled.
      - **monthlyDisabled** (required) — type `boolean`; nullable. Whether monthly plans are disabled.
      - **paymentsState** (required) — type `string`; nullable. The publication's payments state.
      - **freeTrialEnabled** (required) — type `boolean`; nullable. Whether a free trial is offered.
      - **pausedUntil** (required) — type `string`; nullable. ISO 8601 timestamp, or null when Substack does not publish one.
      - **emailBannerUrl** (required) — type `string`; nullable. The email banner image URL.
      - **copyright** (required) — type `string`; nullable. The copyright line the publication prints.
      - **logoUrl** (required) — type `string`; nullable. The publication's logo URL.
      - **wideLogoUrl** (required) — type `string`; nullable. The publication's wide logo URL.
      - **coverImageUrl** (required) — type `string`; nullable. The publication's cover image URL.
      - **foundingPlanName** (required) — type `string`; nullable. The name of the founding-member plan.
      - **hasRecommendations** (required) — type `boolean`; nullable. Whether the publication recommends others.
      - **benefits** (required) — type `object`. The benefit lists for each subscription tier.
      - **author** (required) — type `object`. The publication's main author.
      - **audience** (required) — type `object`. Approximate audience figures the publication prints. These are bands, not counts.
      - **contributors** (required) — type `array`. People with a byline on the publication.
        - _items:_
      - **sections** (required) — type `array`. The publication's sections.
        - _items:_
      - **links** (required) — type `array`. Links the publication shows.
        - _items:_
      - **plans** (required) — type `array`. The subscription plans the publication offers.
        - _items:_
      - **podcast** (required) — type `object`. The publication's podcast, when it has one.
  - **page** (required) — type `object`. Page-number pagination state for the current page.
    - **page** (required) — type `integer`; minimum: 0. Current page (0-based).
    - **hasMore** (required) — type `boolean`. True when another page exists.
    - **nextPage** (required) — type `integer`; minimum: 0; nullable. The next page number; null on the last page.
- **meta** (required) — type `object`. Metadata describing the request and billing outcome.
  - **requestId** (required) — type `string`; minLength: 1. Unique request identifier for tracing this API call.
  - **creditsCharged** (required) — type `integer`; minimum: 0. Credits charged for this request.
  - **version** (required) — type `string`; enum: v1. Public API version that served the response.

### Example JSON (found)

```json
{
  "data": {
    "lookupStatus": "found",
    "restrictedReason": null,
    "publicationId": 89120,
    "query": "climate",
    "results": [
      {
        "post": {
          "id": 42503142,
          "publicationId": 89120,
          "slug": "highlights-from-the-comments-on-kids",
          "title": "Highlights From The Comments On Kids And Climate Change",
          "subtitle": "...",
          "description": "...",
          "kind": "newsletter",
          "audience": "everyone",
          "isPaywalled": false,
          "url": "https://www.astralcodexten.com/p/highlights-from-the-comments-on-kids",
          "publishedAt": "2021-10-13T15:08:12.124Z",
          "updatedAt": null,
          "language": "en",
          "bodyHtml": null,
          "bodyIsPreview": false,
          "previewText": null,
          "wordCount": 4924,
          "commentCount": 527,
          "replyCount": 73,
          "reactionCount": 93,
          "reactions": {
            "❤": 93
          },
          "restackCount": 1,
          "commentPermission": "everyone",
          "coverImageUrl": "https://substackcdn.com/image/fetch/$s_!_Neh!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2Ffb86922b-b202-4ae5-b6f2-6a89ff98ba66_768x432.jpeg",
          "coverImageIsSquare": false,
          "coverImageIsExplicit": false,
          "isGeoblocked": false,
          "blockedCountries": [],
          "liveStreamId": null,
          "isPublished": null,
          "isPinned": false,
          "seoTitle": null,
          "seoDescription": null,
          "socialTitle": null,
          "previousSlug": null,
          "nextSlug": null,
          "section": null,
          "tags": [],
          "authors": [
            {
              "id": 12009663,
              "name": "Scott Alexander",
              "handle": "astralcodexten",
              "slug": null,
              "bio": null,
              "photoUrl": "https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2F7b500d22-1176-42ad-afaa-5d72bc36a809_44x44.png",
              "badge": null,
              "badges": null,
              "bestsellerTier": 1000,
              "primaryPublication": null
            }
          ],
          "podcast": null,
          "audio": {
            "url": null,
            "durationSeconds": null,
            "fileSizeBytes": null,
            "mediaType": null,
            "episodeImageUrl": null,
            "items": [
              {
                "postId": 42503142,
                "voiceId": "en-US-JennyNeural",
                "audioUrl": "https://substack-video.s3.amazonaws.com/video_upload/post/42503142/tts/bf5ed8ce-ae9b-4c9c-a15b-2163f84e62ec/en-US-JennyNeural.mp3",
                "type": "tts",
                "status": "completed"
              }
            ]
          },
          "video": null
        },
        "highlights": [
          {
            "segments": [
              {
                "text": "Several people argued I was underestimating the downsides of ",
                "isHighlighted": null
              }
            ]
          }
        ]
      }
    ],
    "publications": [
      {
        "id": 89120,
        "name": "Astral Codex Ten",
        "subdomain": "astralcodexten",
        "customDomain": "www.astralcodexten.com",
        "apexDomain": null,
        "url": "https://www.astralcodexten.com",
        "host": "www.astralcodexten.com",
        "description": "P(A|B) = [P(A)*P(B|A)]/P(B), all the rest is commentary.",
        "language": "en",
        "kind": "newsletter",
        "createdAt": "2020-08-30T04:18:18.308Z",
        "firstPostAt": "2020-08-30T21:01:57.050Z",
        "hasPosts": true,
        "isExplicit": false,
        "isInviteOnly": false,
        "isFlagged": false,
        "noIndex": false,
        "isOnSubstack": false,
        "commentsEnabled": true,
        "notesEnabled": false,
        "defaultCommentSort": "oldest_first",
        "annualDisabled": false,
        "monthlyDisabled": false,
        "paymentsState": "enabled",
        "freeTrialEnabled": false,
        "pausedUntil": null,
        "emailBannerUrl": null,
        "copyright": "Scott Alexander",
        "logoUrl": "https://substackcdn.com/image/fetch/$s_!bGN2!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2F430241cb-ade5-4316-b1c9-6e3fe6e63e5e_256x256.png",
        "wideLogoUrl": null,
        "coverImageUrl": null,
        "foundingPlanName": "Founding Member",
        "hasRecommendations": true,
        "benefits": {
          "free": [
            "Public posts"
          ],
          "paid": [
            "Support me being able to blog more."
          ],
          "founding": []
        },
        "author": {
          "id": 12009663,
          "name": "Scott Alexander",
          "handle": "astralcodexten",
          "slug": "astralcodexten",
          "bio": null,
          "photoUrl": "https://substackcdn.com/image/fetch/$s_!HTBd!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2F7b500d22-1176-42ad-afaa-5d72bc36a809_44x44.png",
          "badge": {
            "type": "bestseller",
            "tier": 1000,
            "handle": null,
            "service": null,
            "url": null
          },
          "badges": null,
          "bestsellerTier": 1000,
          "primaryPublication": null
        },
        "audience": {
          "paidLabel": null,
          "paidOrderOfMagnitude": null,
          "totalLabel": null,
          "totalOrderOfMagnitude": null,
          "freeLabel": null,
          "freeShort": null,
          "chatMembersLabel": null
        },
        "contributors": [
          {
            "id": 12009663,
            "name": "Scott Alexander",
            "handle": "astralcodexten",
            "role": "admin",
            "owner": true,
            "photoUrl": "https://substackcdn.com/image/fetch/f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fbucketeer-e05bbc84-baa3-437e-9518-adb32be77984.s3.amazonaws.com%2Fpublic%2Fimages%2F7b500d22-1176-42ad-afaa-5d72bc36a809_44x44.png",
            "bio": null,
            "badge": {
              "type": "bestseller",
              "tier": 1000,
              "handle": null,
              "service": null,
              "url": null
            },
            "bestsellerTier": 1000
          }
        ],
        "sections": [],
        "links": [],
        "plans": [
          {
            "id": "monthly10usd",
            "nickname": "$10 a month",
            "amount": 1000,
            "currency": "usd",
            "interval": "month",
            "intervalCount": 1,
            "active": true,
            "founding": false
          }
        ],
        "podcast": {
          "exists": false,
          "hasFreeEpisodes": false,
          "hasPaidEpisodes": false,
          "artUrl": null,
          "byline": null,
          "description": null,
          "feedUrl": null,
          "title": null,
          "paidEpisodeArtUrl": null
        }
      }
    ],
    "page": {
      "page": 0,
      "hasMore": true,
      "nextPage": 1
    }
  },
  "meta": {
    "requestId": "req_01example_substack_publications_publication_posts_search",
    "creditsCharged": 1,
    "version": "v1"
  }
}
```

### Machine-readable error codes

When an error JSON body is returned, it may include one of these `error.code` values (derived from the OpenAPI schemas for this operation; additional codes may exist at runtime):

- `bad_request`

## Error handling & retries

Interpret HTTP status codes using the descriptions below. Do not assume a JSON body unless the OpenAPI schema defines one for that status.

- **400**: Invalid request **Retry:** Fix the request; retrying the same invalid payload will not help.
- **401**: Missing or invalid API key **Retry:** Fix the API key first; retrying without changes will not help.
- **402**: Insufficient credits **Retry:** Do not retry without resolving billing/credits (retrying the same request will not help).
- **500**: Unexpected or billing error
- **502**: Lookup could not be completed. **Retry:** May be transient; a few retries with backoff are reasonable.
- **503**: Service temporarily unavailable; safe to retry with backoff. **Retry:** Usually safe to retry with exponential backoff and jitter.

### Suggested client defaults

- Send the API key using the `x-api-key` header on every request.
- On `503` (and sometimes `502`), retry with backoff; cap retries and surface a clear error to the user.
- On `402`, surface an actionable billing message rather than blind retries.

## Examples

### TypeScript SDK

```typescript
import { SocialFetchClient } from "@socialfetch/sdk";

const client = new SocialFetchClient({
  apiKey: process.env.SOCIALFETCH_API_KEY!,
});

const result = await client.substack.searchPublicationPosts({
  publication: "astralcodexten",
  query: "climate",
});

if (!result.ok) {
  console.error(result.error);
} else {
  console.log(result.value.data);
}
```

### Node.js

```javascript
const response = await fetch(
  "https://api.socialfetch.dev/v1/substack/publications/astralcodexten/posts/search?query=climate",
  {
    headers: {
      "x-api-key": "YOUR_API_KEY"
    }
  }
);

const data = await response.json();
console.log(data);
```

### cURL

```bash
curl "https://api.socialfetch.dev/v1/substack/publications/astralcodexten/posts/search?query=climate" \
  -H "x-api-key: YOUR_API_KEY"
```

### Python

```python
import requests

response = requests.get(
    "https://api.socialfetch.dev/v1/substack/publications/astralcodexten/posts/search?query=climate",
    headers={"x-api-key": "YOUR_API_KEY"},
)
data = response.json()
print(data)
```