> For the complete documentation index, see [llms.txt](https://docs.apryse.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.apryse.com/web/get-started/faq/save-load-custom-props.md).

# How to save and load a custom property on an annotation?

World's #1 PDF SDK Library for Web, Mobile, Server, Desktop

The recommended way is to use the [`setCustomData`](https://sdk.apryse.com/api/web/Core.Annotations.Annotation.html#setCustomData) function on annotations.

{% tabs %}
{% tab title="JavaScript" %}
{% code lineNumbers="true" %}

```js
const myCustomAttributeValue = 'some custom data';
myAnnotation.setCustomData('myCustomAttribute', myCustomAttributeValue);
```

{% endcode %}
{% endtab %}
{% endtabs %}

When the PDF is downloaded this data will also be embedded inside the PDF and if you re-open the PDF in WebViewer it will be accessible through the [`getCustomData`](https://sdk.apryse.com/api/web/Core.Annotations.Annotation.html#getCustomData) function.

{% tabs %}
{% tab title="JavaScript" %}
{% code lineNumbers="true" %}

```js
const myCustomAttributeValue = myAnnotation.getCustomData('myCustomAttribute');
```

{% endcode %}
{% endtab %}
{% endtabs %}

Alternatively you can use the [`setCustomSerializeHandler`](https://sdk.apryse.com/api/web/Core.Annotations.html#.setCustomSerializeHandler) and [`setCustomDeserializeHandler`](https://sdk.apryse.com/api/web/Core.Annotations.html#.setCustomDeserializeHandler) APIs, however note that saving an attribute this way will only work if you load XFDF separately from the PDF. If you download the PDF the attribute will not be preserved.

{% tabs %}
{% tab title="JavaScript" %}
{% code lineNumbers="true" %}

```js
const { Annotations } = instance.Core.Annotations;

Annotations.setCustomSerializeHandler(Annotations.Annotation, function(element, pageMatrix, options) {
  options.originalSerialize(element, pageMatrix);
  if (options.annotation.myCustomAttribute) {
    element.setAttribute('attribute-name', options.annotation.myCustomAttribute);
  }
  return element;
});

Annotations.setCustomDeserializeHandler(Annotations.Annotation, function(element, pageMatrix, options) {
  options.originalDeserialize(element, pageMatrix);
  options.annotation.myCustomAttribute = element.getAttribute('attribute-name');
});
```

{% endcode %}
{% endtab %}
{% endtabs %}


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