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What Restic Is

Restic is a backup program: a single command-line tool that copies your files into a repository — a store it manages — in a way that is encrypted, deduplicated, and checkable. It is free, open-source software, written in Go, and it runs on Linux, Windows, and macOS from one binary with no server of its own to install. The repository can live on a disk in the same machine, a disk in another room, or somebody else's storage reached over the network. Restic neither knows nor cares which; it treats them all as places that hold files.

Three words in that first paragraph do the real work, and the whole guide hangs off them:

  • Encrypted. Everything in the repository is encrypted with a key derived from a password you choose at creation. Whoever holds the repository files holds ciphertext. Without the password, the backups are unreadable — including to you, a fact chapter 10 treats with the seriousness it deserves.
  • Deduplicated. Restic cuts files into chunks and stores each distinct chunk once. Backing up the same photograph in two folders, or the same nearly-unchanged document on thirty successive nights, costs the repository almost nothing after the first copy. Chapter 6 proves this with numbers from the lab, not adjectives.
  • Checkable. A repository can be verified: restic check reads its structures, and with --read-data it re-reads and re-validates the stored data itself. A backup you have never tested is a hope; restic at least gives you the test.

Snapshots, not copies

Each run of restic backup produces a snapshot: a complete, browsable picture of the folders you backed up at that moment. Snapshots feel like full copies — you can list one, walk through it, restore any file from it — while physically sharing almost all of their data with the snapshots before and after them. That combination, full-picture semantics on shared storage, is the thing older copy-the-folder backup habits cannot do, and it changes what is practical: keeping a snapshot a night for months stops being a storage problem.

Who it is for

Anyone whose current backup plan is "copy the folder to the external drive when I remember", or a sync tool quietly mirroring deletions as faithfully as files. Restic suits a home folder going to a USB drive, a photo library going to a second machine over SSH, a small server's data going to object storage — the same tool and the same commands at each scale. It asks you to be comfortable at a command line, and it asks you to keep one password safe. In exchange it does not ask for an account, a subscription, or trust in anyone's cloud.

What it is not

  • Not synchronisation. Sync tools (Syncthing, Dropbox, rsync without history) make two places the same, including the mistakes. Restic keeps history: yesterday's mistake does not overwrite last week's good copy.
  • Not a disk imager. It backs up files and folders, not bootable whole-machine images. Restoring a system means reinstalling the system and restoring its files — a workable plan, but a different one.
  • Not a database backup tool by itself. It faithfully copies a live database's files, which may not be a consistent database. Dump first, then back up the dump — chapter 12's recipes say how.
  • Not set-and-forget. It has no daemon and no schedule of its own; your system's scheduler (cron, systemd timers, Task Scheduler) runs it. And its pruning and checking only happen when something runs them.
  • Not anonymous magic. The encryption is strong and the design is public, but the password is a single point of total failure. Chapter 4 starts there for a reason.

The one-sentence version

If your files matter, restic turns "copy them somewhere, sometimes" into encrypted, deduplicated snapshots you can browse, restore from, and verify — for the price of learning a dozen commands and guarding one password.