Quicksand

Quicksand is a free Mac app that syncs your recently opened files with the Cloud.

Quicksand takes the hassle out of cloud storage: every time you open a file, it's automatically synced to your favorite cloud storage solution, without you even having to think about it. This means that you'll always have access to the files you've been working on recently, wherever you are, whenever you need them.

You'll quickly forget that Quicksand is even there, but you'll love the fact that that any file you use on your Mac is instantly available to you everywhere you go!

Quicksand is highly customizable. To make sure that you don't run out of cloud storage space, you can easily tell Quicksand not to sync more than a certain number of files, never to use more than a certain amount of your cloud storage space, or only to sync files of certain filetypes or in certain folders. Quicksand works just the way you want it to!