You can now add links next to attachments in the Confluence UI via Confluence plugins. That means you can, for example, add a link to an action in your plugin that allows viewing of attachments online:
Actually, this has been possible since Confluence 2.8. The links will show up on content’s attachments view in Confluence 2.8+. In Confluence 2.10+, the links will also show up on the list of attachments shown by the attachments macro. Why didn’t you hear about this before? We just started using this new feature ourselves to make links for attachments that can be viewed with the Office Connector (links coming in Confluence 2.10), and we realized we had neglected to document the ability to create the links earlier.
To create an attachment link in your plugin, add a web UI plugin module with location “system.attachment” to your plugin’s atlassian-plugin.xml. You can add a condition to control which attachments will have the link. And don’t worry, we now have documentation for you: here’s the documentation for the web UI plugin module, where you’ll find a description of the system attachment location and some other locations that are fairly new. Another of the newer locations is “system.comment.action”, which allows you to add links next to edit and remove in comments.