There are many alternatives to Syncthing for Mac if you are looking for a replacement. The best Mac alternative is Resilio Sync , which is free. If that doesn't suit you, our users have ranked more than 50 alternatives to Syncthing and many of them are available for Mac so hopefully you can find a suitable replacement. Other interesting Mac alternatives to Syncthing are FreeFileSync (Free, Open Source), Rclone (Free, Open Source), MediaFire (Freemium) and Onionshare (Free, Open Source).
Internxt Drive offers a fully secure cloud storage experience. Files uploaded to Internxt Drive are client-side encrypted, and only the user holds the decryption key of these. Additionally, prior to being uploaded, files are fragmented. Servers only host encrypted shards.
brig is a distributed & secure file synchronization tool with version control. It is based on IPFS, written in Go and will feel familiar to git users. Think of it as a swiss army knife for file synchronization or as a peer to peer alternative to Dropbox.
nFreezer (for encrypted freezer) is an encrypted-at-rest backup tool, designed specifically for the case when the destination server is untrusted. With nFreezer, the data is safe on the destination server even if a malicious user gets root access to it.
Lsyncd watches a local directory trees event monitor interface (inotify or fsevents). It aggregates and combines events for a few seconds and then spawns one (or more) process(es) to synchronize the changes. By default this is rsync.