# Change feed

URL: https://docs.healthcare.dev/reference/datasets/change-feed

```http
GET https://api.healthcare.dev/v1/changes
```

Records added, changed or retired by each published release of a dataset. Oldest first by default (for feed consumers); `order=desc` returns the most recent first. Page with `cursor`. The first (baseline) load of a dataset writes no change rows.

Requires an API key: `Authorization: Bearer hdev_live_...`. See [Authentication](/authentication).

## Query parameters

| Name | Type | Required | Description | Example |
| --- | --- | --- | --- | --- |
| `dataset` | string | yes | Dataset id from `/v1/datasets` | `icd10cm` |
| `since` | string (date-time) | no | Only changes published after this time |  |
| `limit` | integer | no | Page size, 1 to 1000 (default 100) | `100` |
| `order` | "asc" \| "desc" | no | asc = oldest first (default), desc = newest first | `asc` |
| `cursor` | string | no | Opaque cursor from `links.next` |  |

## Examples

**curl**

```sh
curl "https://api.healthcare.dev/v1/changes?dataset=icd10cm&limit=100" \
  -H "Authorization: Bearer $HDEV_API_KEY"
```

**TypeScript**

```ts
const res = await fetch("https://api.healthcare.dev/v1/changes?dataset=icd10cm&limit=100", {
  headers: { Authorization: `Bearer ${process.env.HDEV_API_KEY}` },
});
const { data, meta } = await res.json();
```

**Python**

```python
import os
import requests

res = requests.get("https://api.healthcare.dev/v1/changes?dataset=icd10cm&limit=100", headers={"Authorization": f"Bearer {os.environ['HDEV_API_KEY']}"})
body = res.json()
```

## Response

Changes

```json
{
  "data": [
    {
      "dataset": "icd10cm",
      "key": "E11.A",
      "kind": "added",
      "data_version": "2026.1",
      "published_at": "2026-10-01T06:00:00Z"
    }
  ],
  "meta": {
    "source": "cms-icd10",
    "data_version": "2026.1",
    "retrieved_at": "2026-10-24T12:00:00Z",
    "license": "Public domain (CMS). Reference data, not medical advice."
  },
  "links": {
    "self": "/v1/changes?dataset=icd10cm&limit=100",
    "next": "/v1/changes?dataset=icd10cm&limit=100&cursor=eyJrIjoiRTExLjkifQ"
  }
}
```

### Fields

| Field | Type | Always present | Description |
| --- | --- | --- | --- |
| `dataset` | string | yes |  |
| `key` | string | yes |  |
| `kind` | "added" \| "changed" \| "retired" | yes |  |
| `data_version` | string | yes |  |
| `published_at` | string (date-time) | yes |  |

## Errors

Errors are `application/problem+json` ([RFC 9457](https://www.rfc-editor.org/rfc/rfc9457)). Branch on `type`, not on `title`. See [Errors](/errors).

| Status | `type` | When |
| --- | --- | --- |
| 400 | `invalid-request` | A parameter or the body failed validation; `errors` lists each field. |
| 401 | `unauthorized` | Missing, malformed or revoked API key. |
| 404 | `not-found` | No record with that id (retired records are still returned). |
| 429 | `rate-limited / quota-exceeded` | Too many requests per second (retry after `Retry-After`), or the monthly quota is used up. |
| 503 | `dataset-unavailable / unavailable` | The dataset has no published version yet, or the service is degraded. |