Good to know

Yes. LinSync is free software under the GNU General Public License, version 3 or later. There's no paid version, no account and no adverts.

Yes, with no backup to set up. Open Expert, set Right side to Another computer, then drag the file across, or pick it and press Copy selected. It's copied once, straight there, and nothing is saved as a backup unless you press Save as a backup. The other computer needs to be a Mac or Linux computer. How it works.

Yes, since release 12. In New backup, choose A cloud service as where it goes, then Connect a cloud: Google Drive, Dropbox, OneDrive, Box and pCloud sign in once in your web browser, and Amazon S3, Backblaze B2, Wasabi, Cloudflare R2 and other S3 storage take an access key. No cloud app is needed. More about clouds.

No. LinSync asks Google only for the files it creates itself (Google's drive.file permission), so it can't see or change anything else in your Drive. The key Google gives it stays on your computer. To take its access away, use Cloud services in LinSync's More menu, or myaccount.google.com/permissions. Privacy.

They have no official way for other apps to connect. Choose them as a folder on this computer instead (they show up in Places on a Mac), and their own apps upload what LinSync puts there.

Yes, since release 12. In Expert, set Left side to Another computer and pick one, then do the same on the right (or pick a cloud), and drag files across. They pass through the computer you're using, in a temporary folder that's deleted straight after. Both other computers need to be Macs or Linux computers. How it works.

After copying, it compares the copy's fingerprint (its SHA-256 checksum) with the original's. If even one bit is different, they don't match, so the file is copied again and checked again; if it's still wrong, the old file is kept and you're told. On another computer, the fingerprint is worked out there; a cloud gives its own. It's on for every backup. More.

A little. The original's fingerprint is taken while it's read for copying, and the copy's is worked out where it is, so nothing travels twice. In testing, 50 files (60 MB) to another computer took 2.4 seconds checked, against 1.8 unchecked. For a backup where speed matters more, untick Check every copy on New backup's last page, or in Expert.

Yes, since release 10. In Simple, New backup asks "How should it arrive?": as files, as one zip, or as one zip with a password, and a zip backup makes a new dated zip each time it runs. In Expert, the button under Copy selected chooses the same for each copy. More about zips.

With the password, and an app that understands AES-256 zips: 7-Zip on Windows (free, from 7-zip.org), Keka or The Unarchiver on a Mac, or the file manager on most Linux desktops (or 7z x). The unzip built into Windows and macOS can't open them. If the password is lost, nobody can open the zip, so write it down somewhere safe.

For a backup that runs by itself, in your Mac's Keychain, on Linux in the system's password store (GNOME Keyring or KWallet, through secret-tool), and on Windows in Windows' own Credential Manager. LinSync never writes it into its own files or onto a command line, and forgets it when you delete the backup. A password zip sent from Expert asks for the password each time and doesn't keep it.

Yes, since release 14. A backup that runs by itself needs its password kept somewhere safe, and on Windows LinSync now keeps it in Windows' own Credential Manager, as it uses the Keychain on a Mac. More.

Zip passwords can only use plain letters, numbers, spaces and keyboard symbols. Other unzip apps read accents and other alphabets differently, so a zip locked with them might never open; 7-Zip refuses them for zips, and LinSync tells you as you type.

Yes, since release 14. Tick Lock it when you connect a cloud, or press Make a locked folder in it… in Cloud services. Files and their names are scrambled on your computer before they're sent, and only your password opens them, so write it down. More.

In Expert, click the tick boxes in front of the files: as many as you like, with no keys to hold. Then drag any of them and they all go. Select all above each side ticks everything in that folder.

It can, so there's a speed limit in More… → Settings: 2, 5 or 10 MB/s for your other computers and clouds. Copies on your own computer are never slowed.

Yes, unless you tick Scheduled backups wait for the charger in Settings. Then, on battery, it waits up to three hours for mains power. A backup you start yourself always runs.

Since release 14, once a day it reads one small file, linsync.co.uk/latest.json, to see if there's a newer release. Nothing about you, your computer or your files is sent with it. Switch it off in More… → Settings. Privacy.

No. Files go straight from your computer to your drive, your other computer or your cloud service. Between two other computers they pass through the one you're using, never through us. LinSync has no servers of its own and no account to sign in to.

Not at home. You need it only to reach a computer that isn't on the same home network; at home, LinSync connects over your own network. Tailscale has a free plan for personal use, and LinSync offers to set it up for you.

Yes, with Tailscale. Install it on both computers and sign in, and your home computer gets a name that works from anywhere, such as home-pc. In LinSync, press Find my computers to pick it (or type the name) and the backup runs just as it does at home. Scheduled backups work too, as long as both computers are on and Tailscale is running.

If a backup mirrors or syncs that deletion, the file isn't thrown away: it goes into .linsync_archive on the other side, sorted by date, and stays there for 30 days (or as long as you choose). Copy mode never deletes anything at all. To get it back, click More…, then Get a file back (since release 14): pick the date, choose it, and press Put back. How.

The Windows installer and the Mac app aren't code-signed yet, which costs money every year. On Windows choose More info, then Run anyway; on a Mac go to System Settings, Privacy & Security, Open Anyway. You can check each download against its SHA-256 checksum on the download page first.

Not yet. A Windows PC can send backups to a Mac or Linux computer, and to drives and cloud folders. Receiving on Windows is on the list.

Yes. Run linsync classic for the original window with every setting on one screen. Your backups are shared between the two.

In ~/.config/linsync/ on Linux, ~/Library/Application Support/LinSync/ on a Mac, and AppData\Roaming\LinSync on Windows.

Email dan@brilliant-hosting.com with your computer, its system version and what you were doing.