# contextData: Adding Extra Data to Assets

Ango Hub allows you to attach arbitrary text data to any [asset](/core-concepts/assets.md), in such a way that it will appear, together with the asset, in the final [export](/data/importing-and-exporting-annotations/exporting-annotations.md). We call this data `contextData`.

contextData is always a JSON dictionary with key/value pairs, for example:

```json
"contextData": {
    "key1": "value1",
    "key2": "value2"
}
```

## Uploading contextData

contextData can be added to assets when uploading them:

* Through the [SDK](/sdk/sdk-documentation.md)
* Through the *Upload Data URL* function in the UI.

### SDK

* when using the [`upload_files()`](/sdk/sdk-documentation.md#upload_files-project_id-file_paths-storage_id-batches) function as documented.
* when using the [`upload_files_cloud()`](/sdk/sdk-documentation.md#upload_files_cloud-project_id-assets-integration_id-batches) function as documented.

### Upload Data URL

1. From your project dashboard, navigate to the *Assets* tab.
2. Click on the *Add Data* button.
3. Enter the *Upload Data URL* section.
4. Prepare a JSON containing your asset URLs paired with contextData, like so:

```json
[
  {
    "data": "https://i.imgur.com/CzXTtJV.jpg",
    "externalId": "cute-cat.jpg",
    "contextData": {
      "key1": "value1",
      "key2": "value2"
    }
  },
  {
    "data": "https://i.imgur.com/OB0y6MR.jpg",
    "externalId": "cute-dog.jpg",
    "contextData": {
      "key3": "value3",
      "key4": "value4"
    }
  }
]
```

5. Drag and drop the JSON onto the upload box and upload. Your assets will have the contextData paired with them.

## Downloading/Viewing contextData

From your project, navigate to the *Export* tab and click on *Export V3.* You will obtain the contextData of each of your assets in the export:

```json
[{
  "asset": "https://asset.com/asset.jpg",
  "externalId": "7b7c4903a2ab4b22a47462af682dd7c6",
  "contextData": {
    "key1": "value1"
  },
  "metadata": {},
  "batches": [],
  "task": {
    "taskId": "64e4758e73c32b0015749157",
    "..."
    ],
    "classifications": [],
    "relations": []
  }
}]
```


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