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). SpiderOak distinguishes itself from competition in provision of encryption, in provision for syncing files and folders across multiple devices, and in automatic de-duplication of data. To achieve this, SpiderOak uses a layered approach to encryption, using a combination of 2048 bit RSA and 256-bit AES.