Syncthing
FreeOpen-source continuous file synchronization — decentralized Dropbox alternative
About Syncthing
Syncthing is a continuous file sync tool that works peer-to-peer without a central server — it's like Dropbox, except your files sync directly between your own devices without touching anyone else's infrastructure. Written in Go, around 65,000 GitHub stars. Install it on two or more devices, define which folders to share, and it keeps them in sync automatically. Works on Windows, Mac, Linux, BSD, and Android. No accounts, no cloud, no subscription fees ever. Uses the Block Exchange Protocol to sync only changed blocks within files rather than whole files, making it efficient on slow connections. The web UI is functional but not beautiful — this is a tool for people who care about privacy and control, not ease of use. The iOS situation is the main Reddit complaint: there's no official iOS client, and the third-party Mobius Sync app costs money and isn't open source. Android works great. Sync conflicts produce versioned backup copies of the conflicting file rather than merging, which is the right behavior but can pile up and confuse users expecting Dropbox-style automatic conflict resolution.
Key Features
Pricing Plans
Free
- Unlimited devices
- Unlimited files
- E2E encryption
- Peer-to-peer sync
- No cloud required
Pros
- True privacy — data never touches a cloud
- Completely free forever
- Lightweight and reliable
- Works across all platforms
Cons
- Requires devices to be online to sync
- No web interface for file access
- No built-in sharing with non-users
Best For
- Developers syncing project files and configs between multiple personal machines without cloud storage
- Privacy-focused users who want file sync without any data leaving their own devices
- Homelab setups where you want reliable sync between a home server and laptops or workstations
Not Ideal For
- iOS users — there's no free official client, and the third-party option isn't open source
- Non-technical users who find conflict files confusing and want Dropbox-style simplicity
Potential Deal Breakers
- No iOS client — the only option is a paid third-party app that isn't open source
- No browser-based file access — you need to be at one of the synced devices to open files
- Sync conflicts produce versioned backup files rather than merging — these pile up if ignored
Data & Privacy
Peer-to-peer file sync with no central server. All data transferred directly between your devices with end-to-end encryption. No cloud, no accounts, no tracking. Complete privacy by architecture.
Who Is This For?
Hands-on tested May 2026
Signup Experience
No account or signup required — download Syncthing for your OS and run it. The web UI opens at localhost:8384 on first launch. Adding a device requires exchanging device IDs between the two machines — copy the ID from one machine, add it on the other, and both sides confirm the connection. Sharing a folder selects which connected devices receive it. The initial sync starts immediately after both sides confirm. Setup between two personal computers takes about 10 minutes for the first pair. Mobile apps for Android and iOS connect using a QR code scan of the device ID.
For Home Users
The best tool for syncing files between personal devices without any cloud service. Sync documents, photos, and project files between a laptop, desktop, and phone — all encrypted in transit, peer-to-peer, with no data touching a third-party server. Works on the local network for fast transfers and over the internet for remote sync. No storage limits, no subscription, no per-file fees. The trade-off versus Dropbox or Google Drive is that both devices must be online and reachable simultaneously for sync to occur — there is no central storage that holds files when a device is offline. For households with always-on home servers, this limitation disappears entirely.
For Business Users
Syncthing works for small teams syncing project files between workstations — design assets, code repositories, or shared document folders. No central server is required and no data leaves the team infrastructure. For teams with an always-on server acting as a hub device, Syncthing provides continuous background sync that keeps all workstations current. The lack of versioning history, centralized access control, and audit logging makes it unsuitable for regulated business use. For business file sharing requiring access management, version history, and browser-based access, Nextcloud or SharePoint are more appropriate. Syncthing is best for technical teams comfortable with self-managed infrastructure who want simple reliable sync at zero cost.
Our Verdict
Syncthing is the purest answer to 'I want Dropbox without Dropbox.' Peer-to-peer, Go-based, no accounts, works everywhere except iOS. Setup takes 15 minutes and then it just runs. It's not a full Google Drive replacement — no browser file access, no collaboration — but for straight-up file sync between devices you own, it's hard to beat.