BorgBackup (Borg) is a deduplicating backup program for archiving. Files are split into content-defined chunks, and identical chunks are stored only once, across files, backups and machines. You can choose compression with lz4, zstd, zlib or lzma. Data is encrypted on the client with AES-256 and authenticated with HMAC-SHA256, so the backup server stores only ciphertext. A backup runs as a single command with no daemons or agents, to a local disk or to any machine reachable over SSH. Archives can be mounted as a file system. Borg runs on Linux, macOS and FreeBSD, among others.
Borg is free open-source software under the BSD licence and is maintained by a community, The Borg Collective, rather than by a single company. There is therefore no vendor that receives your data: you run the software yourself and decide where the repository lives, for example on your own servers or with a European hosting provider. Thanks to client-side encryption, the storage location itself does not need to be trusted. The source code can be reviewed independently.