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Base64 Images Not Displaying in Embedded HTML Documents Using eSignature API

  • October 20, 2025
  • 1 reply
  • 26 views
S
Newcomer
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Hi DocuSign Community!

I'm experiencing an issue with displaying base64-encoded images in HTML templates used for embedded signing via the eSignature API.
I'm using HTML templates with <img> tags that contain base64-encoded images in the src attribute (using data: URLs). The images display perfectly when viewing the HTML in a standard web browser, but they disappear when the document is embedded using the DocuSignJS SDK for signing.
Technical Details:
  • API Used: DocuSign eSignature API with embedded signing
  • SDK: DocuSignJS SDK (https://js.docusign.com/bundle.js)
  • Image Format: Base64-encoded images using data:image/[format];base64,[data] syntax
  • Implementation: HTML templates with embedded <img> tags

 

Are there any known limitations or specific requirements for displaying base64-encoded images in HTML templates when using embedded signing? Is there an alternative approach I should consider for including images in signable HTML documents?

Documentations references:

Envelope creation

Embedded Signing using focused view

Signable HTML
 

Thank you for your help.

1 reply

B
Docusign Employee
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  • Byungjae.ChungDocusign Employee
  • Docusign Employee
  • October 22, 2025

It seems there's no issue with your technical details. However, I wasn't able to reproduce the same problem. I have tested the embedded signing using both the Classic signing session (opening the embedded signing URL in the browser) and the Focused view signing session (using the Docusign JS bundle), but the image was loaded without issue. More information about each signing session is here: https://developers.docusign.com/docs/esign-rest-api/esign101/concepts/embedding/embedded-signing/

I also created the template with the HTML with the image, but the image was loaded in the focused view signing session without issue.

For your reference, you can also test whether the image loads without issue using the documents object below:

"documents": [
        {
            "name": "Example contract",
            "documentId": "1",
            "htmlDefinition": {
                "source": "<div><img src=\"data:image/gif;base64,R0lGODlhDwAPAKECAAAAzMzM/////wAAACwAAAAADwAPAAACIISPeQHsrZ5ModrLlN48CXF8m2iQ3YmmKqVlRtW4MLwWACH+H09wdGltaXplZCBieSBVbGVhZCBTbWFydFNhdmVyIQAAOw==\"alt=\"Base64 encoded image\" width=\"150\" height=\"150\"/></div>"
            }
        }
    ]

 

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