# lemmy.search_communities

**stable** **Advanced**

Search Lemmy communities.

`GET /v1/lemmy/search_communities`

## What you get

A list of Lemmy 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 |
| --- | --- | --- | --- | --- | --- |
| `instance` | string | no | - | Known Lemmy instance (allowlisted), default lemmy.world | max 253 chars; must match `[a-z0-9.-]{3,253}`; trimmed, lowercased |
| `q` | string | yes | (required) | Search query | max 200 chars; trimmed, repeated spaces collapsed |

## Request

```bash
curl "https://api.onekey.dev/v1/lemmy/search_communities?q=python" \
  -H "x-api-key: YOUR_API_KEY"
```

```python
import requests

res = requests.get(
    "https://api.onekey.dev/v1/lemmy/search_communities",
    params={"q": "python"},
    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({ q: "python" });
const res = await fetch(`https://api.onekey.dev/v1/lemmy/search_communities?${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 Lemmy response, recorded and returned in Onekey's shape. Fields the platform does not provide are `null`.

```json
{
  "success": true,
  "data": [
    {
      "content": {
        "id": "6090",
        "title": "Python",
        "text": "Welcome to the [Python community](https://programming.dev/c/python) on the programming.dev Lemmy instance!\n\n##### [📅 Events](https://pycon.org/#calendar)\n\n::: spoiler Past\nNovember 2023\n- [PyCon Ireland 2023](https://python.ie/pycon-2023/), 11-12th\n- [PyData Tel Aviv 2023](https://pydata.org/telaviv2023/) 14th\n\nOctober 2023\n- [PyConES Canarias 2023](https://2023.es.pycon.org/), 6-8th\n- [DjangoCon US 2023](https://2023.djangocon.us/), 16-20th ([!django 💬](https://programming.dev/post/90489))\n\nJuly 2023\n- [PyDelhi Meetup](https://www.meetup.com/pydelhi/events/294140277/), 2nd\n- [PyCon Israel](https://2023.pycon.org.il/), 4-5th\n- [DFW Pythoneers](https://www.meetup.com/dfwpython/events/293749882/), 6th\n- [Django Girls Abraka](https://djangogirls.org/en/abraka/), 6-7th\n- [SciPy 2023](https://www.scipy2023.scipy.org/) 10-16th, Austin\n- [IndyPy](https://www.meetup.com/indypy/events/293963956), 11th\n- [Leipzig Python User Group](https://www.meetup.com/leipzig-python-user-group/events/294330224/), 11th\n- [Austin Python](https://www.meetup.com/austinpython/events/293844612/), 12th\n- [EuroPython 2023](https://ep2023.europython.eu/), 17-23rd\n- [Austin Python: Evening of Coding](https://www.meetup.com/austinpython/events/294089607/), 18th\n- [PyHEP.dev 2023 - \"Python in HEP\" Developer's Workshop](https://indico.cern.ch/event/1234156/timetable/#20230725.detailed), 25th\n\nAugust 2023\n- [PyLadies Dublin](https://www.meetup.com/pyladiesdublin/events/293742378/), 15th\n- [EuroSciPy 2023](https:/",
        "createdAt": "2023-06-12T23:51:06Z"
      },
      "entity": {
        "name": "python",
        "url": "https://programming.dev/c/python",
        "stats": {
          "followers": 8053
        }
      },
      "media": {
        "thumbnailUrl": "https://programming.dev/pictrs/image/1d99f7cb-50e7-4994-94c4-fd23f30209b7.png"
      },
      "ext": {
        "posts": 735
      },
      "engagement": {
        "comments": 3602
      }
    },
    {
      "content": {
        "id": "107",
        "title": "Python",
        "text": "News and discussions about the programming language Python\n\n---",
        "createdAt": "2019-04-25T21:49:00Z"
      },
      "entity": {
        "name": "python",
        "url": "https://lemmy.ml/c/python",
        "stats": {
          "followers": 3649
        }
      },
      "media": {
        "thumbnailUrl": null
      },
      "ext": {
        "posts": 109
      },
      "engagement": {
        "comments": 102
      }
    }
  ],
  "metadata": {
    "platform": "lemmy",
    "endpoint": "search_communities",
    "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 |
| --- | --- | --- |
| `community.id` | `content.id` | `toString` |
| `community.name` | `entity.name` | - |
| `community.title` | `content.title` | - |
| `community.description` | `content.text` | - |
| `community.actor_id` | `entity.url` | `safeUrl` |
| `community.icon` | `media.thumbnailUrl` | `safeUrl` |
| `community.published` | `content.createdAt` | `toIsoDate` |
| `counts.subscribers` | `entity.stats.followers` | `toNumber` |
| `counts.posts` | `ext.posts` | `toNumber` |
| `counts.comments` | `engagement.comments` | `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).