Open-source Synology C2 alternatives

Restic is a backup program designed to be fast, efficient and secure. It runs on Linux, macOS and Windows, with support for FreeBSD and OpenBSD, and ships as a single command-line tool written in Go. It is released under the BSD-2-Clause license, and the project keeps documentation and a Discourse forum for questions.

Backups are stored in a repository that you create with an init command and protect with a password, and the README warns that losing the password means losing the data. Each run saves a snapshot, and deduplication keeps repeated data from using extra space. Files can be restored with a restore command, or the repository can be mounted through FUSE so past snapshots can be browsed. Restic can store backups in a local directory, over SFTP, on an HTTP REST server, in Amazon S3 or S3-compatible storage, OpenStack Swift, Backblaze B2, Azure Blob Storage, Google Cloud Storage, or through rclone.

SeaweedFS is a distributed storage system built to store very large numbers of files and serve them quickly. A single weed binary can provide an S3-compatible object store, a POSIX file system and S3 Tables for lakehouse use, all over the same data. The project is written in Go and released under the Apache-2.0 license.

Its design aims for constant-time disk access per file, and capacity grows by starting another volume server. Cloud storage can be cached or tiered transparently, and replication and erasure coding are supported. The same process can also run the master, volume servers, a filer, WebDAV, an Iceberg REST catalog and an Admin UI. You can start with one command, Docker, Docker Compose or Helm on Kubernetes, or build from source. The README includes comparisons with HDFS, Ceph, GlusterFS, MooseFS and MinIO.

RustFS is a distributed object storage system built in Rust. It offers S3 API compatibility for supported features, and is meant to coexist with, or take over from, platforms like MinIO and Ceph that also speak the S3 API. The project is open source under the Apache 2.0 license and highlights that this avoids the restrictions of AGPL-licensed alternatives.

The feature list includes a scalable, fault-tolerant distributed architecture, an S3 compatibility matrix that tracks current coverage, and native support for the OpenStack Swift API and Keystone authentication. It is tuned for data lakes, AI and big data workloads, and the README says it was designed for easy deployment and management. A status legend marks features as available, preview or planned, so check the documentation for the current state of each capability before relying on it.

Ceph is a distributed storage platform that offers object, block and file storage from one software-defined system. It is designed to scale across many servers and provide highly available storage, and it is written mainly in C++.

Repository topics show the range of protocols and features it covers: S3-compatible object storage, block storage, a POSIX distributed file system with FUSE access, protocols such as NFS, SMB, iSCSI and NVMe over Fabrics, and replication and erasure coding for data protection. The topics also mention Kubernetes and HDFS.

Most of Ceph is dual-licensed under the LGPL version 2.1 or 3.0, with some code in the public domain or under BSD-style licenses, which is why the repository lists the license as 'Other'. The documentation uses CC-BY-SA-3.0, and contributions need a Signed-off-by line without copyright assignment. Ceph is deployed on your own hardware or cloud infrastructure.

Duplicati is a free, open-source backup client that securely stores encrypted, incremental and compressed backups on cloud storage services and remote file servers. According to its README it is licensed under the MIT license and available for Windows, macOS and Linux, and it is written in C#.

Data is encrypted with AES-256 or GNU Privacy Guard before it is uploaded. Only the first backup is a full copy, and later backups are differential to save bandwidth and storage. A built-in scheduler keeps backups current, and an integrated updater announces new releases. Supported destinations include Amazon S3, Backblaze B2, Box, Dropbox, FTP, Google Cloud and Drive, MEGA, Microsoft Azure and OneDrive, Storj, SFTP, WebDAV and others.

Releases are GPG-signed, and the project offers a forum, an online manual and several update channels from stable to more experimental builds. Because the backup client runs on your own machines and sends data to storage you choose, it suits individuals and small teams who want client-side encrypted backups without a vendor-hosted service.

Kopia is an open-source backup and restore tool that creates encrypted snapshots of selected files and directories. It does not image a whole machine; instead you choose the folders that matter and Kopia stores the snapshots in the location you pick, whether that is cloud storage, a network server or a local disk.

Compression, deduplication, error correction and end-to-end encryption controlled by the user are built in, so repeated backups stay small and the storage provider never sees readable data. Supported destinations include Amazon S3 and S3-compatible services, Azure Blob Storage, Backblaze B2, Google Cloud Storage, WebDAV, SFTP and, experimentally, a subset of Rclone backends.

Both a command-line interface and a graphical interface are included, so the tool suits advanced users and people who prefer a GUI. It runs on Windows, macOS and Linux, is written in Go and is licensed under Apache-2.0. The project site offers installation instructions and a step-by-step getting started guide.

BorgBackup, usually called Borg, is a backup program that stores files as content-defined chunks. Identical chunks are kept only once across files, machines and years of history, so a daily full backup costs little more than the changes made since the previous run. This makes long retention periods practical on modest storage.

Repositories are protected with authenticated AES encryption, which means a backup server only ever sees ciphertext and does not need to be trusted. Compression is configurable, with options such as lz4 for speed, zstd as a balance and zlib or lzma for smaller output. Archives can be mounted as an ordinary filesystem through FUSE so earlier versions of files can be browsed like folders.

Borg is written in Python, has been developed since 2015, and is free software under a BSD license. It installs on Linux, macOS, BSD and other systems from distribution packages, single-file binaries or pip. The project site provides a demo, documentation, a community page and commercial support services.

Backrest is a backup tool you reach through a web browser, built on restic. Its web interface wraps the restic command-line tool so you can create repositories, browse snapshots and restore files, and it can run in the background to schedule snapshots and orchestrate repository health tasks.

It supports importing existing restic repositories and cron-scheduled backups and maintenance such as prune, check and forget. Notifications can be sent through Discord, Slack, Shoutrrr, Gotify or Healthchecks, and pre and post backup hooks can run shell scripts. All restic storage backends are supported, including S3, B2, Azure, GCS, local and SFTP, along with rclone remotes. The interface can be reached locally or remotely, which suits NAS deployments, and the restic CLI remains available for advanced operations.

Backrest is written in Go with a TypeScript interface, licensed under GPL-3.0 and distributed as a standalone binary whose only dependency is restic, downloaded on first run. It runs on Linux, macOS, Windows, FreeBSD and Docker.