# QR codes

Source: https://developers.leonai.io/docs/guides/qr-codes/

Every short link has a QR image served publicly by the redirect host at
`GET /:shortCode/qr` — **no authentication required**. Because it's a plain image URL,
you can build it yourself; the planned [TypeScript SDK](https://developers.leonai.io/docs/sdks/) (not published yet) builds
it for you instead of making an API call.

## Build a QR URL

```ts
const qrUrl = leonai.qr.buildUrl('spring-sale', {
  size: 512,
  format: 'svg', // png | svg | dataurl
  color: '#111111',
  backgroundColor: '#FFFFFF',
  errorCorrectionLevel: 'H', // L | M | Q | H
  margin: 4,
});
// -> https://short.leonai.io/spring-sale/qr?size=512&format=svg&...
```

## Options

| Option                 | Values                  | Notes                                           |
| ---------------------- | ----------------------- | ----------------------------------------------- |
| `size`                 | pixels                  | Width/height of the square image                |
| `format`               | `png`, `svg`, `dataurl` | `dataurl` returns an inline `data:` URI         |
| `color`                | hex                     | Foreground (module) color                       |
| `backgroundColor`      | hex                     | Background color                                |
| `errorCorrectionLevel` | `L`, `M`, `Q`, `H`      | Higher levels tolerate more damage/logo overlay |
| `margin`               | integer                 | Quiet-zone modules around the code              |

## Use it directly

Since the URL is public, drop it straight into an `<img>` tag, a print asset, or a
PDF:

```html
<img
  src="https://short.leonai.io/spring-sale/qr?size=512&format=png"
  alt="Scan for the Spring Sale"
  width="256"
  height="256"
/>
```

Dynamic QR codes point at the short link, so you can change the destination later
(via [link update](https://developers.leonai.io/docs/guides/links/#update)) without reprinting the code.