borg README

The project's README from github.com/borgbackup/borg. As one markdown file: README.md.

This is borg2!

Please note that this is the README for (unstable) Borg2 / master branch.

For general project infos, versioned docs, screen casts, please see there:

https://www.borgbackup.org/

Borg2 is currently in beta testing and might get major and/or breaking changes between beta releases (and there is no beta to next-beta upgrade code, so you will have to delete and re-create repos).

Thus, DO NOT USE BORG2 FOR YOUR PRODUCTION BACKUPS! Please help with testing it, but set it up additionally to your production backups.

What is BorgBackup?

BorgBackup (short: Borg) is a deduplicating backup program. Optionally, it supports compression and authenticated encryption.

The main goal of Borg is to provide an efficient and secure way to back up data. The data deduplication technique used makes Borg suitable for daily backups since only changes are stored. The authenticated encryption technique makes it suitable for backups to targets not fully trusted.

See the installation manual_ or, if you have already downloaded Borg, docs/installation.rst to get started with Borg.

.. _installation manual: https://borgbackup.readthedocs.io/en/master/installation.html

Main features


**Space efficient storage**
  Deduplication based on content-defined chunking is used to reduce the number
  of bytes stored: each file is split into a number of variable length chunks
  and only chunks that have never been seen before are added to the repository.

  A chunk is considered duplicate if its id_hash value is identical.
  A cryptographically strong hash or MAC function is used as id_hash,
  e.g. (hmac-)sha256 or (keyed) blake3.

  To deduplicate, all the chunks in the same repository are considered, no
  matter whether they come from different machines, from previous backups,
  from the same backup or even from the same single file.

  Compared to other deduplication approaches, this method does NOT depend on:

  * file/directory names staying the same: So you can move your stuff around
    without killing the deduplication, even between machines sharing a repo.

  * complete files or time stamps staying the same: If a big file changes a
    little, only a few new chunks need to be stored - this is great for VMs or
    raw disks.

  * The absolute position of a data chunk inside a file: Stuff may get shifted
    and will still be found by the deduplication algorithm.

  Supported chunkers:

  * fastcdc (the default)
  * buzhash64 (improved), buzhash (as in borg 1.x)
  * toeplitz-aes / rabin-aes / goldilocks-aes (keyed, AES-based; they make
    chunk-boundary fingerprinting attacks much harder)
  * fixed (fixed blocksize, optionally with a differently sized header)

**Speed**
  * performance-critical code (chunking, compression, encryption) is
    implemented in C/Cython, using SIMD (NEON / AVX2 / AVX-512) where that
    is a win - the scan kernel is picked per platform
  * local caching
  * quick detection of unmodified files

**Data encryption**
    All data can be protected client-side using 256-bit authenticated encryption
    (AES-OCB or chacha20-poly1305), ensuring data confidentiality, integrity and
    authenticity.

    If you do not need confidentiality, there are also modes that only
    authenticate (``authenticated-sha256`` / ``authenticated-blake3``) and
    modes that do neither (``none-sha256`` / ``none-blake3``).

**Hashing**
    You can choose between HMAC-SHA256 and Blake3.

**Obfuscation**
    Optionally, Borg can actively obfuscate, e.g., the size of files/chunks to
    make fingerprinting attacks more difficult.

**Compression**
    All data can be optionally compressed:

    * lz4 (super fast, low compression)
    * zstd (wide range from high speed and low compression to high compression
      and lower speed)
    * zlib (medium speed and compression)
    * lzma (low speed, high compression)

**Off-site backups**
    Borg can store data on any remote host accessible via misc. protocols:

    * ``rest://`` (REST-http-over-stdio-over-ssh) and ``http(s)://``
      (REST-http-over-tcp). Significant performance gains can be achieved with
      these by having a remote agent (borg must be installed on the repo server).
    * ``sftp://``
    * ``s3://`` / ``b2://``
    * ``rclone:`` - lots of protocols / providers supported by rclone

**Backups mountable as file systems**
    Backup archives are mountable as user-space file systems for easy interactive
    backup examination and restores (e.g., by using a regular file manager).

**Easy installation on multiple platforms**
    We offer single-file binaries that do not require installing anything -
    you can just run them on these platforms:

    * Linux (x86_64, arm64)
    * macOS (arm64, x86_64)
    * FreeBSD (x86_64)
    * Windows (x86_64, MSYS2/MINGW borg.exe, experimental)

    Borg also runs on these platforms, but you need to install it from a
    package or from source:

    * NetBSD (xattrs, but no ACLs)
    * OpenBSD (no xattrs/ACLs support)
    * illumos / Solaris (xattrs, but no ACLs)
    * Cygwin (experimental)
    * Windows Subsystem for Linux (WSL) on Windows 10/11 (experimental)

**Free and Open Source Software**
  * security and functionality can be audited independently
  * licensed under the BSD (3-clause) license, see `License`_ for the
    complete license

Easy to use
~~~~~~~~~~~

For ease of use, set the BORG_REPO environment variable::

    $ export BORG_REPO=/path/to/repo

Create a new backup repository (see ``borg repo-create --help`` for encryption options)::

    $ borg repo-create --encryption=aes256-ocb --key-location=repokey

Create a new backup archive::

    $ borg create docs ~/Documents

Now do another backup, just to show off the great deduplication::

    $ borg create -v --stats docs ~/Documents
    Creating archive "docs" in repository /path/to/repo
    Repository: /path/to/repo
    Archive name: docs
    Archive fingerprint: 7714aef97c1a24539cc3dc73f79b060f14af04e2541da33d54c7ee8e81a00089
    Time (nominal): Mon, 2026-08-03 19:57:35 +0200
    Time (start):   Mon, 2026-08-03 19:57:35 +0200
    Time (end):     Mon, 2026-08-03 19:57:35 +0200
    Duration: 0.01 seconds
    Number of files: 24
    Original size: 29.73 MB
    Deduplicated size: 520 B
    ...


For demo videos, check out our homepage: https://www.borgbackup.org/#demo

Helping, donations and bounties, becoming a Patron
--------------------------------------------------

Your help is always welcome!

Spread the word, give feedback, help with documentation, testing or development.

You can also give monetary support to the project, see here for details:

https://www.borgbackup.org/#fund

Thanks to everyone who has helped so far - these are the people with the most
commits, see `FAME.md <https://github.com/borgbackup/borg/blob/master/FAME.md>`_
for the full list:

.. image:: https://raw.githubusercontent.com/borgbackup/borg/master/FAME.svg
   :alt: Borg contributors by commit count
   :target: https://github.com/borgbackup/borg/blob/master/FAME.md

Links
-----

* `Main website <https://www.borgbackup.org/>`_
* `Releases <https://github.com/borgbackup/borg/releases>`_,
  `PyPI packages <https://pypi.org/project/borgbackup/>`_ and
  `Changelog <https://github.com/borgbackup/borg/blob/master/docs/changes.rst>`_
* `GitHub <https://github.com/borgbackup/borg>`_ and
  `Issue tracker <https://github.com/borgbackup/borg/issues>`_.
* `Web chat (IRC) <https://web.libera.chat/#borgbackup>`_ and
  `Mailing list <https://mail.python.org/mailman/listinfo/borgbackup>`_
* `License <https://borgbackup.readthedocs.io/en/master/authors.html#license>`_
* `Security contact <https://borgbackup.readthedocs.io/en/master/support.html#security-contact>`_

Compatibility notes
-------------------

EXPECT THAT WE WILL BREAK COMPATIBILITY REPEATEDLY WHEN MAJOR RELEASE NUMBER
CHANGES (like when going from 0.x.y to 1.0.0 or from 1.x.y to 2.0.0).

NOT RELEASED DEVELOPMENT VERSIONS HAVE UNKNOWN COMPATIBILITY PROPERTIES.

THIS IS SOFTWARE IN DEVELOPMENT, DECIDE FOR YOURSELF WHETHER IT FITS YOUR NEEDS.

Security issues should be reported to the `Security contact`_ (or
see ``docs/support.rst`` in the source distribution).

.. start-badges

|doc| |build| |coverage| |bestpractices|

.. |doc| image:: https://readthedocs.org/projects/borgbackup/badge/?version=master
        :alt: Documentation
        :target: https://borgbackup.readthedocs.io/en/master/

.. |build| image:: https://github.com/borgbackup/borg/actions/workflows/ci.yml/badge.svg?branch=master
        :alt: Build Status (master)
        :target: https://github.com/borgbackup/borg/actions

.. |coverage| image:: https://codecov.io/github/borgbackup/borg/coverage.svg?branch=master
        :alt: Test Coverage
        :target: https://codecov.io/github/borgbackup/borg?branch=master

.. |bestpractices| image:: https://www.bestpractices.dev/projects/271/badge
        :alt: Best Practices Score
        :target: https://www.bestpractices.dev/projects/271

.. end-badges

borg (borgbackup/borg)

cryptography
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13.9K ·GitHub
Borg
What is this?BorgBackup is a deduplicating backup program that supports optional compression and authenticated encryption. It's designed to let you run efficient, secure daily backups since it only stores changed data.
Is this a GUI app or a command-line tool?It's a command-line program (CLI), driven by commands like 'borg repo-create' and 'borg create'. Backup archives can also be mounted as a filesystem for browsing with a regular file manager.
How do I get started with it?Set a BORGREPO environment variable pointing to your repo path, run 'borg repo-create --encryption=aes256-ocb --key-location=repokey' to create the repository, then 'borg create docs ~/Documents' to make your first archive.
Do I need Python installed, or can I just run a binary?Single-file binaries are offered for Linux, macOS, FreeBSD and (experimentally) Windows that need no installation at all; on other platforms (NetBSD, OpenBSD, illumos/Solaris, Cygwin, WSL) you install from a package or source, which requires Python.
Is it safe to use the version in this branch for my real backups?No — this README is for the unstable Borg2/master branch, which is still in beta with no upgrade path between beta releases, so repos must be deleted and recreated between betas. The README explicitly warns not to use it for production backups.
Which platforms can I actually run Borg on?It runs natively on Linux (x86_64, arm64), macOS (arm64, x86_64), FreeBSD, and experimentally on Windows via MSYS2/MINGW, plus from-source support for NetBSD, OpenBSD, illumos/Solaris, Cygwin and WSL.
Can I back up to a remote server over SSH?Yes, Borg can store data on remote hosts via SSH-based protocols like rest:// and sftp://, as well as S3/B2 and any provider rclone supports; for better performance a remote agent of Borg should be installed on the repo server.
Does Borg encrypt my data before sending it off-site?Yes, all data can be protected client-side with 256-bit authenticated encryption (AES-OCB or chacha20-poly1305) before it leaves your machine, ensuring confidentiality, integrity and authenticity.
How does Borg's deduplication actually work?Each file is split into variable-length chunks using content-defined chunking, and only chunks never seen before (identified by a cryptographic hash like SHA256 or BLAKE3) get stored, no matter which machine, backup, or file they came from.
What compression algorithms can I pick?You can choose lz4 for speed, zstd for a balance of speed and ratio, zlib for medium speed/compression, or lzma for maximum compression at the cost of speed.
Can I browse my backups like a regular folder?Yes, backup archives can be mounted as user-space file systems, letting you interactively examine or restore files using a regular file manager.
What hashing or chunking options does Borg support for extra security against fingerprinting?Borg supports several chunkers including fastcdc, buzhash variants, and keyed AES-based chunkers (toeplitz-aes, rabin-aes, goldilocks-aes) that make chunk-boundary fingerprinting attacks harder, and it can optionally obfuscate file/chunk sizes.
What are similar projects?restic, tailcat, acme.sh, turbocrypt, bpytop, age, tmux, onedump
Which topics is it in?deduplication, compression, freebsd, cryptography, backup, ssh, sysadmin, encryption, bsd, command-line, devops, security
Creator
borgbackup
Size
44.6 MB
Stars
13.9K
Updated
CommitOct 14Release1.4.5Jul 18
Age
11y
Commits · 90 Days