How do I add previous versions of my modpack to be able to download?

[ThePumpkin5822]

I'm trying to do something similar with the official packs, but it looks like they're using a method I can't so I won't be surprise if what I'm requesting isn't available. I need a way to allow my users to download older versions of my mod pack I've created. So, say I updated to version 1.1. I want them still able to downgrade to 1.0 to see if they have the same issues and if the pack gets old enough, for going back on the old days. If you're curious, I'm using dropbox as my downloader for the launcher. However I'm willing to move it, as it's being a pain.