FreeFileSync — a sync tool that shows you what’s really changing
FreeFileSync is an open-source program that focuses on keeping folders in step, whether they’re on the same machine, a server across the hall, or a network share in another building. It’s not trying to replace full-blown backup suites — its strength is in comparing two locations, showing you exactly what’s different, and then making them match.
It runs on Windows, macOS, and Linux. You can set it to sync in both directions, just push updates one way, or keep a perfect mirror. Real-time mode can watch for changes and react instantly, while versioning lets you keep older copies of files you might need later.
Capabilities
| Feature | Description |
| Cross-Platform | Works the same on Windows, Linux, and macOS — no stripped-down ports |
| Multiple Sync Modes | Two-way, mirror, or one-way updates, plus custom rules if you want to get picky |
| Real-Time Option | Watches for file changes instead of running on a timer |
| Versioning Support | Keeps older versions in a separate folder so mistakes aren’t final |
| Network and Remote Paths | Handles SMB shares, FTP/SFTP, or local drives without extra tools |
| Batch Jobs | Save a sync setup and run it later, with or without the GUI |
| Filtering | Skip files by size, date, or extension — handy for avoiding junk |
| Portable Build | Runs from a USB stick, no install needed |
Deployment Notes
FreeFileSync’s preview window is worth using — it’s easy to catch an accidental overwrite before hitting “go.” The real-time sync is light on CPU since it hooks into the OS change notifications. On network jobs, it’s best to have stable connectivity; if the link drops mid-sync, you may end up with mismatched folders. The portable build is a favorite for techs doing quick on-site work.
Quick Start (Windows)
1. Download from https://freefilesync.org
2. Install or unpack the portable ZIP.
3. Pick source and target folders.
4. Choose a sync mode.
5. Run “Compare” to see planned changes.
6. Press “Synchronize” and watch it work.
Usage Scenarios
– Keeping a developer’s local folder in sync with a staging server.
– Mirroring a shared documents folder to a standby NAS.
– Real-time duplication of work files to an external SSD during the day.
– Syncing project files between two offices over VPN.
– Quick, no-install file copies when doing field support.