Open attachment file using the Jira REST API (cloud/server)

I am trying to find a proper way to open a file attached to a Jira issue using the REST API (cloud and server platforms).

I managed to get the details of an issue including its attachments. For example, for a given issue I get the following attachment object.

{
  "attachments": [
     {
	   "self": "https://myinstance.atlassian.net/rest/api/3/attachment/12345", 
	   "id": "12345", 
	   "filename": "image.png", 
	   "author": {...}, 
	   "created": "2025-10-05T15:09:46.973+0200", 
	   "size": 15926,
	   "mimeType": "image/png", 
	   "content": "https://myinstance.atlassian.net/rest/api/3/attachment/content/12345", 
	   "thumbnail": "https://myinstance.atlassian.net/rest/api/3/attachment/thumbnail/12345"
     }
   ]
}

My goal is to minimize the number of requests I make to the API in order to get the final URL of the attachment.

With this in mind I noticed that I can use the following URL to get an attachment:

https://myinstance.atlassian.net/secure/attachment/12345/image.png

Pasting this in the browser or using curl I’m able to get the file (assuming I’m logged in to Jira).

My question: is this a supported URL? I mean, using /secure/… Is this a proper way to download/view an attachment?

The advantage of this for me is that I can easy generate that URL from an attachment w/o having to make additional requests to the API in order to download or view the file.

Why all this? Because I’m implementing a tool that allows users to view issues and attachments from a terminal application. In this scenario, it would be great of I can access the final URL of an attachment w/o extra API requests (avoiding getting the attachment content, etc.)

Thanks for the help.

G.