syncthing/syncthing

Syncthing is a continuous, peer-to-peer file synchronization program. It is for individuals who want their files mirrored between devices they control — laptop, phone, desktop, or a machine at another location — without storing them in a third-party cloud. The project's stated design priorities, in order, are avoiding data loss, resisting attackers, ease of use, and running automatically with minimal user interaction.

How the useful result is produced

Devices sync folders directly with each other over the network rather than through a central service. The README points to a protocol specification for the wire format, BEP v1, while daily use starts from the getting started guide. Because each participant is a full peer, which folders exist and which devices share them are decisions you make per device; there is no account that owns the data.

Two mechanisms change the practical workflow:

• Ignore rules. Folders can exclude patterns, so build outputs, dependency directories such as node_modules, and other disposable files can be kept out of the sync set. A long-time user describes relying on this to sync about 150 GB of pictures, documents and audiobooks instantly across a phone, laptop and desktop on a local network, instead of waiting weeks for a first cloud upload on a slow connection (comment, 2021).
• Untrusted devices. A device can be configured to hold encrypted copies it cannot read, using a passphrase you keep elsewhere. That makes an off-site backup machine or a spare computer at a relative's home useful without granting that location readable access; the same user describes this as a redundancy option (comment, 2021). This is a configuration mode, not a substitute for a backup you can restore on your own.

Ways to run it

The core program runs on common desktop and server systems; the README lists background-run examples in the etc directory and separate GUI wrappers for Windows, macOS and Linux (README, GUI wrappers). A container path is documented separately in the Docker README. Building from source needs a Go toolchain: after checkout, the provided build script produces binaries (build guide).

Conditions worth knowing before adopting

• Releases and updates. Release binaries are GPG-signed, macOS and Windows builds are code-signed, and there is a built-in automatic upgrade path that uses a compiled-in signature; this is disabled in some distribution channels (README). Users installing through a package manager should not assume self-updating works.
• Cost of your own storage. Syncthing removes the subscription, not the storage requirement. A user who tried to replace Dropbox this way found renting a VPS with enough capacity surprisingly expensive (comment, 2025); replies suggest pointing Syncthing at cheap network storage instead (reply, 2025).
• Mobile clients are separate. The Android experience comes from third-party apps and forks with differing reliability and features, including reports of needing manual restarts and a fork offering scheduled sync (comment, 2021, fork recommendation). The core project's README does not promise a first-party mobile client.
• Security reporting. Suspected vulnerabilities should go by email to the security address, not the forum or issue tracker (README).
• Licence. All code is under MPL-2.0, a file-level copyleft licence (README, licence text).

HotRepo's take

HotRepo recorded one weekly Go board observation: +288 for the week with a best rank of #18 on 2026-10-31. With only that single recorded date, it says nothing about sustained or fading interest. The strongest evidence of long-term use here remains narrative: a 2021 discussion thread with 444 points (HN thread) and commenters describing years of use.