KDE Connect: Enabling communication between all your devices

How well does this work for sending a lot of files without re-sending the same file?

I have a desktop + laptop + phone.

When I want to sync a directory with a lot of files I wrote a little shell script that uses rsync to do it. This does require running SSH on my laptop but I can invoke the shell script from my desktop.

Likewise with my phone I want to backup my camera photos, using rsync is nice here to avoid sending thousands of them over every time. I run SSH on my phone with Termux, it was really painless to set up and is only on when I run it. Likewise, I invoke the shell script from my desktop to do the transfer.

For this purpose, I would not suggest KDE Connect.

What you're looking for is something more like SyncThing: https://syncthing.net

I use SyncThing on my phone to back up photos/videos on my phone to my NAS. The UX is not great, but it does sync things correctly 100% of the time. For years on end, I never have to worry about it.

I thought about SyncThing in the past but was reluctant because I don't have a centralized server and I don't always want 1 device to be the definitive source of truth.

For example:

    - On desktop, wrote a blog post
    - On desktop, pushed my blog post folder to my laptop
    - On laptop, publish the blog post 3 days later
    - On laptop, fix a typo and publish the post
    - On desktop, pull in the changes from the laptop

The same type of situations happen with KeePassXC's database file. Sometimes I make an update on my phone or laptop and want it sent to my desktop, other times I make the update on my desktop and want it sent to the other 2 devices.

With SyncThing, would this overwrite files on the wrong device as soon as I "sync"?

Syncthing is very much not about having a centralised source of truth. It gives you options about how things sync - I usually start very paranoid when I set up a sync folder and store all versions of a file if the files are only small, but you can store staggered versions etc.

It will also store all conflicts, which you then can manually resolve.

Another option you have is send-only and receive-only folders.

Like I said, lots of options, a bit of learning but it looks like what you want.