We have free dropbox accounts (dropbox.com)
You then save your capx on your computer and copy it/upload it into the public folder. Here's a little more detail from another post I made:
Re: drop box: in your dropbox directory ie: the dropbox website, there is a folder called PUBLIC. you did not create it, it was there when your dropbox account was created.
Put whatever you want to share in that PUBLIC folder. Then you can share that link. I think you right click on the file in the PUBLIC folder it will give you an option for a shareable link.
Hope it helps!