If you have a Gmail account, odds are you have several gigabytes of storage available (which you, realistically, will probably never use). Take advantage of this freely available online space by using it to backup files to with Gmail Drive.

Gmail Drive is a free tool which creates another drive available in My Computer which you can use to store your files. Of course, you are limited to the rules of Gmail with the files storage which includes (currently) 20 MB max file size and ~60 character file name. Still, most of your files should easily satisfy these requirements.

Keep in mind though, this is not an official tool of Google, so it is limited by what can be done by the developer and there is no guarantee it will work in the future due to Gmail changes.