# substack.search

**stable** **Advanced**

Search posts within a Substack publication.

`GET /v1/substack/search`

## What you get

A list of Substack results in Onekey's unified shape, in `data` (an array). An empty array is a normal, successful answer and is charged like any other; a source that reports "nothing found" as an error returns a free `404 not_found` instead.

## What it costs

- **Advanced · 5 credits** for a fresh fetch, charged only when it succeeds.
- **Free when served from cache (0.2 credit for a cached response over 100 KB).**
- **Free** if the request is invalid (never charged) or the source fails or reports not found (refunded).

## Parameters

| Name | Type | Required | Default | What it is | Constraints |
| --- | --- | --- | --- | --- | --- |
| `pub` | string | yes | (required) | Allowlisted Substack publication host, e.g. www.astralcodexten.com | max 253 chars; must match `[a-z0-9.-]{3,253}`; trimmed, lowercased |
| `q` | string | yes | (required) | Search text | max 100 chars; must match `[^\x00-\x1f]{1,100}`; trimmed, repeated spaces collapsed |

## Request

```bash
curl "https://api.onekey.dev/v1/substack/search?pub=www.astralcodexten.com&q=ai" \
  -H "x-api-key: YOUR_API_KEY"
```

```python
import requests

res = requests.get(
    "https://api.onekey.dev/v1/substack/search",
    params={"pub": "www.astralcodexten.com", "q": "ai"},
    headers={"x-api-key": "YOUR_API_KEY"},
)
body = res.json()

if body["success"]:
    print(body["data"])
else:
    print(body["error"]["code"], body["error"]["message"])
```

```javascript
const params = new URLSearchParams({ pub: "www.astralcodexten.com", q: "ai" });
const res = await fetch(`https://api.onekey.dev/v1/substack/search?${params}`, {
  headers: { "x-api-key": "YOUR_API_KEY" },
});
const body = await res.json();

if (body.success) console.log(body.data);
else console.error(body.error.code, body.error.message);
```

## Recorded response

A real Substack response, recorded and returned in Onekey's shape. Fields the platform does not provide are `null`.

```json
{
  "success": true,
  "data": [
    {
      "content": {
        "id": "138968567",
        "title": "God Help Us, Let's Try To Understand AI Monosemanticity",
        "text": "Inside every AI is a bigger AI, trying to get out",
        "url": "https://www.astralcodexten.com/p/god-help-us-lets-try-to-understand",
        "createdAt": "2023-11-27T21:00:12Z"
      },
      "media": {
        "thumbnailUrl": "https://substack-post-media.s3.amazonaws.com/public/images/e3a2a957-0d98-4d59-8d41-b461c421c9d7_210x136.png"
      },
      "engagement": {
        "likes": 317,
        "comments": 227
      },
      "author": {
        "id": "12009663",
        "displayName": "Scott Alexander",
        "username": "astralcodexten",
        "avatarUrl": "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"
      },
      "ext": {
        "audience": "everyone",
        "wordCount": 2991
      },
      "entity": {
        "slug": "god-help-us-lets-try-to-understand"
      }
    },
    {
      "content": {
        "id": "165939000",
        "title": "Make A Personalized AI Kids' Book",
        "text": "\"AI will probably lead to the end of the world, but in the meantime there will be great [presents]\"",
        "url": "https://www.astralcodexten.com/p/make-a-personalized-ai-kids-book",
        "createdAt": "2025-06-20T05:56:08Z"
      },
      "media": {
        "thumbnailUrl": "https://substackcdn.com/image/fetch/$s_!qYcr!,f_auto,q_auto:good,fl_progressive:steep/https%3A%2F%2Fsubstack-post-media.s3.amazonaws.com%2Fpublic%2Fimages%2F588ed56b-6bf5-4fb7-9636-2c5aacbe0bdb_2548x2372.png"
      },
      "engagement": {
        "likes": 85,
        "comments": 16
      },
      "author": {
        "id": "12009663",
        "displayName": "Scott Alexander",
        "username": "astralcodexten",
        "avatarUrl": "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"
      },
      "ext": {
        "audience": "only_paid",
        "wordCount": 941
      },
      "entity": {
        "slug": "make-a-personalized-ai-kids-book"
      }
    }
  ],
  "metadata": {
    "platform": "substack",
    "endpoint": "search",
    "cached": false,
    "stale": false,
    "age_s": 0,
    "fetched_at": "2026-01-01T12:00:00+00:00",
    "credits_charged": 5,
    "request_id": "7f3a9c2e5b1d4c8fa2e6d0b9c4f18e37"
  },
  "error": null
}
```

## Field mapping

How this endpoint's source fields become Onekey's [unified schema](https://onekey.dev/docs/schema.md). Fields the source lacks come back as `null`.

| Source path | Onekey field | Transform |
| --- | --- | --- |
| `id` | `content.id` | `toString` |
| `title` | `content.title` | - |
| `subtitle` | `content.text` | - |
| `canonical_url` | `content.url` | `safeUrl` |
| `post_date` | `content.createdAt` | `toIsoDate` |
| `cover_image` | `media.thumbnailUrl` | `safeUrl` |
| `reaction_count` | `engagement.likes` | `toNumber` |
| `comment_count` | `engagement.comments` | `toNumber` |
| `publishedBylines.0.id` | `author.id` | `toString` |
| `publishedBylines.0.name` | `author.displayName` | - |
| `publishedBylines.0.handle` | `author.username` | - |
| `publishedBylines.0.photo_url` | `author.avatarUrl` | `safeUrl` |
| `audience` | `ext.audience` | - |
| `slug` | `entity.slug` | - |
| `wordcount` | `ext.wordCount` | `toNumber` |

## Caching and freshness

- Fresh for about 2 minutes. Repeat calls in that window are served from cache and are free.
- Between 2 minutes and 15 minutes the cached copy is still served instantly and marked `stale: true` while Onekey refreshes it in the background.
- If the source is down when a refresh is needed, the last copy can be served for up to 1 hour more (marked stale).
- A "not found" is remembered for 1 minute and is free.
- The cache is shared across all customers, which is what keeps repeat calls cheap.

## What can go wrong

| Status | Code | What to do |
| --- | --- | --- |
| 401 | `unauthorized` | Check the `x-api-key` header. |
| 402 | `insufficient_credits` | [Add credits](https://onekey.dev/pricing); your balance must cover the price. |
| 404 | `not_found` | Unknown endpoint path. |
| 422 | `invalid_params` | Fix the parameters using the table above. Free. |
| 429 | `rate_limited` | Wait `Retry-After` seconds, then retry. |
| 502 | `upstream_error` | The source failed. Refunded; retry with backoff. |

See [Errors](https://onekey.dev/docs/errors.md) for the full list and retry guidance.

Status: stable (verified against the live source).