You can find the free app on the Google Play Store or the Apple App Store.
You can connect up to 3 devices at once on the free tier.
The "Online-only" feature allows you to see all your files on your computer without them taking up space on your hard drive until you actually open them. Tips to Get More Free Space
Accidentally deleted a file? Dropbox saves a version history for 30 days , allowing you to restore deleted items easily.
If you do not want to install any software, you can sign in directly at dropbox.com to upload or download files from any browser. What Do You Get with the Free Plan?