Tresorit is an encrypted cloud storage service that aims to address security and privacy concerns with cloud storage. It uses zero-knowledge encryption where files are encrypted on the client before being uploaded and Tresorit does not have access to decryption keys. Tresorit offers syncing of encrypted files across devices, sharing of encrypted files with others, and public links to shared files that decrypt in the browser without installing software. The company is based in Switzerland and Hungary and stores encrypted user data in EU servers.