How to get Base64Binary format of attachment

SANDEEP28 · ‎03-20-2026

Hello Experts,

I need to send a ServiceNow record attachment to a third-party document API. This API only accepts data in base64Binary format. Is there a method available to retrieve the binary content of an attachment and then convert it into base64?

I referred to a thread that explains how to fetch the binary using a REST API call and then convert it to base64 using the GlideStringUtil API. After obtaining the content in base64Binary format, I tested it by uploading to a “base64-to-file” website. While the file was created, the content turned out to be empty.

https://www.servicenow.com/community/developer-forum/attachments-api-converting-binary-files-to-base...

I want to ensure that the base64Binary output is correct and represents the actual attachment data.

@Ankur Bawiskar

Ankur Bawiskar · ‎03-20-2026

@SANDEEP28

yes it has limitation for 5MB

see if this helps

var gr = new GlideRecord('sys_attachment');
	gr.get('d7ff2c044f96cc90fc11fa218110c746');

	var StringUtil = new GlideStringUtil();
	var gsis = GlideSysAttachmentInputStream(gr.sys_id.toString());
	var ba = new Packages.java.io.ByteArrayOutputStream();
	gsis.writeTo(ba,0,0);
	ba.close();
	var base64EncodedData = StringUtil.base64Encode(ba.toByteArray());
gs.info(base64EncodedData);

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Regards,
Ankur
✨ Certified Technical Architect || ✨ 10x ServiceNow MVP || ✨ ServiceNow Community Leader

View solution in original post

Tanushree Maiti · ‎03-20-2026

Hi @SANDEEP28

You can check this article :https://www.servicenow.com/community/developer-forum/converting-the-attachment-into-base64-encoded-s....

Please mark this response as Helpful & Accept it as solution if it assisted you with your question.
Regards
Tanushree Maiti
ServiceNow Technical Architect
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Ankur Bawiskar · ‎03-20-2026

@SANDEEP28

usually attachments are sent with their base64encoded data

what do you mean by base64Binary?

did they give any example for this?

💡 If my response helped, please mark it as correct ✅ and close the thread 🔒— this helps future readers find the solution faster! 🙏

Regards,
Ankur
✨ Certified Technical Architect || ✨ 10x ServiceNow MVP || ✨ ServiceNow Community Leader

SANDEEP28 · ‎03-20-2026

@Ankur Bawiskar They confirmed that it should be base64 encoded of raw binary data

Ankur Bawiskar · ‎03-20-2026

@SANDEEP28

you can use this sample script to get bas64encoded data of file in global scope

var attGr = new GlideRecord('sys_attachment');
  attGr.addQuery('sys_id', '3fd6017407d3dc50540bf2508c1ed027');
  attGr.query();
  if(attGr.next())
        {
   var gsu = (typeof GlideStringUtil != 'undefined') ? (GlideStringUtil) : (Packages.com.glide.util.StringUtil); //few versions support the first one, other supports second
   var gsa = (typeof GlideSysAttachment != 'undefined') ? (new GlideSysAttachment()) : (new Packages.com.glide.ui.SysAttachment());
   var attachmentData = gsa.getBytes(attGr);
   var attachment = String(Packages.java.lang.String(attachmentData));
   gs.info(attachment); //the data in the file will be printed as String
   var encData = GlideStringUtil.base64Encode(attachmentData); // data of one attachment at a time
   gs.info(encData);
}

💡 If my response helped, please mark it as correct ✅ and close the thread 🔒— this helps future readers find the solution faster! 🙏

Regards,
Ankur
✨ Certified Technical Architect || ✨ 10x ServiceNow MVP || ✨ ServiceNow Community Leader