In this guide, we will learn how to replace images within a template and generate a video.

Image Properties:

• url: URL of the image content.
• asset_id: Asset ID of the image content.
• fit: Adjustment of image or video to fit in a area, options: cover, contain, crop, or none. More Info

Creating Template through the Interface

To create templates, visit HeyGen Template page and click on Create Template. You can then set variables and change variable names using the toolbar's API icon.

As you can see, we have assigned a variable name to our image element. In this tutorial, we will demonstrate how to change this image using the Template API.

Get a List of Your Templates

See detailed API reference
Using the following API request you will get a list of your templates that you have created in the HeyGen interface, obtain your template_id from here.

curl --location 'https://api.heygen.com/v2/templates' \
     --header 'accept: application/json' \
     --header 'x-api-key: <your-api-key>'

{
  "error": null,
  "data": {
    "templates": [
      {
        "template_id": "<template_id>",
        "name": "<name>",
        "thumbnail_image_url": "<thumbnail_image_url>"
      },
      ...
    ]
  }
}

Retrieve Template Elements

See detailed API reference
To retrieve template elements for a specific template, use this API request. Get the variable you want to change from here.

curl --location 'https://api.heygen.com/v2/template/<template_id>' \
     --header 'accept: application/json' \
     --header 'x-api-key: <your-api-key>'

{
  "error": null,
  "data": {
    "variables": {
      "poolside_image": {
        "name": "poolside_image",
        "type": "image",
        "properties": {
          "url": "<url>",
          "asset_id": null,
          "fit": "contain"
        }
      }
    }
  }
}

Modify Template Elements and Generate Video

See detailed API reference
To change template elements and generate videos, you will need to submit an API request as follows. In the request body, specify the elements you want to modify by providing the appropriate object within the variables section.

curl --location 'https://api.heygen.com/v2/template/<template_id>/generate' \
     --header 'X-Api-Key: <your-api-key>' \
     --header 'Content-Type: application/json' \
     --data '{
  "caption": false,
  "title": "New Video",
  "variables": {
    "poolside_image": {
      "name": "poolside_image",
      "type": "image",
      "properties": {
        "url": "https://files.heygencdn.com/prod/movio/preset/image/origin/556f811b701548e588c7504906cd571c.jpg",
        "asset_id": null,
        "fit": "contain"
      }
    }
  }
}'

{
  "error": null,
  "data": {
    "video_id": "<video_id>"
  }
}

You will receive a video_id after your request. To check the video's status and retrieve further details, you can use the video_status API endpoint.

And using the Template API, we changed our image and generated our new video, here is the before and after:

You can also use images and videos interchangeably within templates. Here is how to replace an image with a video or vice versa.

Conclusion

In this guide, we've walked you through the process of replacing images within a template video using HeyGen's Template API. By following the steps outlined here, you can seamlessly modify image elements to create customized videos that suit your specific needs.