# QuickChart Agent Notes

QuickChart is an HTTP API for generating static images of Chart.js charts, QR codes, and barcodes. It is commonly used in email, SMS, PDFs, chatbots, automation tools, and reports where client-side rendering is not available.

## Request guidance

- Prefer POST JSON for generated chart configs. GET URLs are useful for small hand-written examples, but agents often produce configs that are too long or need URL encoding.
- Validate before retrying. Use `/api/validate-chart` for chart configs and `/api/validate-qr` for QR payloads to get structured JSON errors.
- Use `/openapi.json` for parameter names, response types, and limits.
- For charts, send Chart.js config in the `chart` field. If the config contains Javascript functions, send `chart` as a string.
- Set `version` to `"4"` for Chart.js v4 syntax. The default is Chart.js v2.
- Set `format` to `png` unless the caller asks for `svg`, `webp`, `jpg`, `pdf`, or `base64`.
- Include `width` and `height` explicitly when output dimensions matter.
- Use `Authorization: Bearer YOUR_API_KEY` or the `key` field for authenticated requests.

## Chart validation example

POST `https://quickchart.io/api/validate-chart`

```json
{
  "version": "4",
  "width": 700,
  "height": 360,
  "format": "png",
  "chart": {
    "type": "bar",
    "data": {
      "labels": ["Jan", "Feb", "Mar"],
      "datasets": [{ "label": "Revenue", "data": [120, 150, 180] }]
    }
  }
}
```

POST the same body to `https://quickchart.io/chart` to receive image bytes.

## QR validation example

POST `https://quickchart.io/api/validate-qr`

```json
{
  "text": "https://example.com",
  "format": "png",
  "size": 300,
  "margin": 4
}
```

POST the same body to `https://quickchart.io/qr` to receive image bytes.

## Natural-language chart generation

POST `https://quickchart.io/natural/config`

```json
{
  "description": "bar chart showing revenue Jan-Mar with values 120, 150, 180",
  "width": 700,
  "height": 360,
  "backgroundColor": "white"
}
```

The response includes a generated Chart.js config string, a saved chart image URL, and a chart editor URL. Treat generated configs as drafts and validate them before embedding in production workflows.