Guide for labeling HTML data.

The HTML editor is a powerful way for you to annotate data that must be visualized in a specific manner for your annotation workforce. When you are annotating an HTML file, Labelbox will render the HTML page in the pane where our editor would normally render.

The HTML file will render where the asset and editor are normally displayed.

The HTML file will render where the asset and editor are normally displayed.

Import HTML data

For information on importing HTML files to Labelbox, see our docs on importing HTML.


Data row size limit

To view the maximum size allowed for a data row, visit our limits page.

Supported annotation types

Below are the annotation types that you may include in your ontology for labeling image data. The HTML editor currently only supports classification-type annotations (radio, checklist, and free-form text).

Import annotationsExport annotations
Radio classificationSee payloadSee payload
Checklist classificationSee payloadSee payload
Free-form text classificationSee payloadSee payload

Sample use cases

Some common use cases for the HTML editor are:

  • Comparing two objects
  • Doing ranking tasks on multiple assets
  • Classifying text that must be formatted in a specific manner
  • Annotating public webpages that have been saved as HTML files

Let's expand on two of these examples below.

Comparison of different products

One common use case among our customers is to do a comparison task between two objects or products. This is especially important for any team-building algorithms to rank or compare similar objects.

In order to visualize the two products and all the characteristics of the products, we were able to create a custom HTML page that renders all the information needed to help the annotation team add the necessary classification annotations


A custom HTML that can pull in information to compare products. For more details about this, please create a support ticket.

Annotating public websites

In order to annotate websites, you will need to first download the webpages of interest as HTML files. This can be done programmatically or manually as seen below:


Navigate to a page and right-click to save it as an HTML page.

Once you have the website saved as an HTML file, you can either directly upload it to Labelbox or store it in your cloud storage and send Labelbox a URL link to the HTML. After the HTML page has been uploaded to a dataset in Labelbox, you can queue it for labeling and see that the website is rendered in the labeling flow.


The website is loaded into Labelbox as an HTML file.


Direct linking to webpages via public URL not supported

Most websites do not support other webpages or applications to open their pages in iframes as a security best practice.

As a result, if you try to link public websites (such as or they will not render in the HTML editor, even if they are HTML pages.