I've been using it for (almost) everything and it has always work perfectly:

I keep my phone's picture in sync with my personal computers ("send only" so I can remove old photos when my SD card is getting full).

I sync a "media" folder where I dump all the music and video I download with the youtube-dl CLI (a "yt" alias makes sure the files are stored in the right directory with some custom parameters).

I sync my KeepassXC databases (work and personal), between my personal Linux laptop, my Android phone and my work MacbookPro. Databases can be merged in a single click if there's any conflict (happens very rarely). I love the Android secure autofill service and fingerprint quick unlock

I use a "temp" folder to drag'n drop stuff between computers so I can file it properly on the right device. On Android, I prefer to use the Syncthing "sharing intent" to make any file/media available on my other devices in just a tap.

I also have installed Syncthing on my Android TV, and occasionally drop HD movies that I download on my phone over P2P (I have a pretty fast connection, so it's easier for me to choose a move from my phone, while in commute, have it download in a few seconds, and either stream it to my TV via Chromecast or open it from the synced folder through Kodi)

This really is a dream setup.

I love it as well, but my one gripe with the Android app is that it does not support read/write sync on external storage (SD cards). This means, in my case, that I have to share photos from my phone in a read-only fashion. It's not a deal-breaker by any means, but it's annoying, because if I want to add photos to my collection that were obtained elsewhere (e.g. my underwater camera), I have to transfer those files to my phone first in order for them to properly propagate to all my other devices.

Here is the related issue: https://github.com/syncthing/syncthing-android/issues/29

I would suspect that if you reconfigure your SDCard to be internal storage then it will work again. This is a limit of Android permissions that happened a couple of major versions ago (I use a different tool for file transfer and I remember when it stopped being able to transfer files to external storage).

I suggest to use https://f-droid.org/en/packages/com.github.catfriend1.syncth... and setup the synced folder on the SD Card as a subdirectory of the app data folder. It's worked well with an old phone (until I replace it with one that no SD card but 128+ GB of storage)

Syncthing is in dire need of an iOS client. There's an unofficial one, but it was unmaintained and didn't sync with recent versions of Syncthing last I checked.

Is it a technical limitation, insufficient developers, or a license issue? IIRC GPL doesn't work with the store.

I believe just insufficient developers. It seems like they're open to someone taking it on: https://forum.syncthing.net/t/on-syncthing-ios-port-again/89...

License is MLP 2.0.

https://github.com/syncthing/syncthing/issues/4995

I feel like there must be some iOS limitations as well. Dropbox can't even sync files in the background, so if I take a bunch of photos, I have to leave it running and touch the screen every couple of minutes in order to get all the photos uploaded. I feel like Dropbox apps are generally pretty good, and this was way janky, and had to be an iOS limitation, but I'm not 100% sure.

iOS apps (including Dropbox) can sync data in the background, but it's a bit janky. You have to give the app permission to access location services. It'll upload a bit of data in the background every time your phone location changes.

I use syncthing for all my personal file syncing. It is so useful and secure to boot!