Kopia is a fast and secure open-source backup/restore tool that allows you to create [encrypted](https://kopia.io/docs/features/#end-to-end-zero-knowledge-encryption) snapshots of your data and save the snapshots to [remote or cloud storage](https://kopia.io/docs/features/#save-snapshots-to-cloud-network-or-local-storage) of your choice, [to network-attached storage or server](https://kopia.io/docs/features/#save-snapshots-to-cloud-network-or-local-storage), or [locally on your machine](https://kopia.io/docs/features/#save-snapshots-to-cloud-network-or-local-storage). Kopia does not 'image' your whole machine. Rather, Kopia allows you to backup/restore any and all files/directories that you deem are important or critical.

Kopia has both [CLI (command-line interface)](https://kopia.io/docs/features/#both-command-line-and-graphical-user-interfaces) and [GUI (graphical user interface)](https://kopia.io/docs/features/#both-command-line-and-graphical-user-interfaces) versions, making it the perfect tool for both advanced and regular users. You can read more about Kopia's unique [features](https://kopia.io/docs/features/) -- which include [compression](https://kopia.io/docs/features/#compression), [deduplication](https://kopia.io/docs/features/#backup-files-and-directories-using-snapshots), [end-to-end 'zero knowledge' encryption](https://kopia.io/docs/features/#end-to-end-zero-knowledge-encryption), and [error correction](https://kopia.io/docs/features/#error-correction) -- to get a better understanding of how Kopia works.

Kopia supports saving your [encrypted](https://kopia.io/docs/features/#end-to-end-zero-knowledge-encryption) and [compressed](https://kopia.io/docs/features/#compression) snapshots to all of the following [storage locations](https://kopia.io/docs/features/#save-snapshots-to-cloud-network-or-local-storage):

A `repository` is the storage location where your snapshots are saved; Kopia supports [cloud/remote, network, and local storage locations](../features#save-snapshots-to-cloud-network-or-local-storage) and all repositories are [encrypted](../features/#end-to-end-zero-knowledge-encryption) with a password that you designate.

Remember to select a secure _repository password_. The password is used to [decrypt](../features/#end-to-end-zero-knowledge-encryption) and access the data in your snapshots.

* [End-to-End 'Zero Knowledge' Encryption](#end-to-end-zero-knowledge-encryption)

Kopia creates snapshots of the files and directories you designate, then [encrypts](#end-to-end-zero-knowledge-encryption) these snapshots before they leave your computer, and finally uploads these encrypted snapshots to cloud/network/local storage called a [repository](../repositories/). Snapshots are maintained as a set of historical point-in-time records based on [policies](#policies-control-what-and-how-filesdirectories-are-saved-in-snapshots) that you define.

* mount the contents of a snapshot as a local disk so that you can browse and copy files/directories from the snapshot as if the snapshot is a local directory on your machine

* restore all files/directories contained in a snapshot to any local or network location that you designate

* selectively restore individual files from a snapshot

All data is encrypted before it leaves your machine. Encryption is baked into the DNA of Kopia, and you cannot create a backup without using encryption. Kopia allows you to pick from two state-of-the-art encryption algorithms, [AES-256](https://en.wikipedia.org/wiki/AES256) and [ChaCha20](https://en.wikipedia.org/wiki/ChaCha20).

Kopia encrypts both the content and the names of your backed up files/directories.

The data is encrypted using per-content keys which are derived from the 256-bit master key that is stored in the repository. The master key is encrypted with a password you provide. This means that anyone that does not know the password cannot access your backed up files and will not know what files/directories are contained in the snapshots that are saved in the repository. Importantly, the password you provide is never sent to any server or anywhere outside your machine, and only you know your password. In other words, Kopia provides your backups with end-to-end 'zero knowledge' encryption. However, this also means that you cannot restore your files if you forget your password: there is no way to recover a forgotten password because only you know it. (But you can [change your password](../faqs/#how-do-i-change-my-repository-password) if you are still connected to the repository that stores your snapshots.)

* [pgzip](https://github.com/klauspost/pgzip)

* [s2](https://github.com/klauspost/compress/tree/master/s2)

* [zstd](https://github.com/klauspost/compress/tree/master/zstd)