I use syncthing often and find it incredibly useful. Thanks for the work!
I use it to sync my Obsidian Vault over my different devices and it's perfect. No need of the paying sync solution...
Great tool but has its quirks. Be careful doing cross platform syncing. What's a legal filename on macos/linux may not be legal on Windows (e.g. "?" in a filename) If something slips through it's probably easier just to scrub the broken sync config and start again.
Does Syncyhing uses a third party relay, or coordinator server?
100% recommended.
syncthing seems pretty solid to me and I've used it a little, but...
There's pushback on the killer feature that I want. I want to be able to sync photos from my phone and clear them automatically so I don't run out of room. I've been told there are ways to do this but they all feel brittle. Syncthing should be in a position to do this safely. E.g., I have 3 destinations and set a policy that photos can be cleared from my phone when they've reached 2/3.