High Quality Content by WIKIPEDIA articles! SpiderOak is an online backup tool for Windows, Mac and Linux users to back up, share, sync, access and store their data using an off-site server. SpiderOak allows the user to backup any given folder of his/her computer. SpiderOak uses encrypted cloud storage and client-side encryption key creation, so even employees of SpiderOak cannot access users` information (this is the `zero-knowledge` data encryption). However, that can`t be assured due to its client`s closed source nature.