In order of personal preference:

scp (sftp)

rsync/openrsync

nfs

host files on an ftp server with ftpd

hosting files on an http server with httpd

https://github.com/positive-intentions/chat

It uses webrtc for P2P connections.

Syncthing?

Syncthing

OnionShare

why not something as basic as sftp?

pairdrop.net maybe?

It’s mainly for local network, but you can do internet transfers.

https://github.com/schlagmichdoch/pairdrop#features

Croc, although it’s command-line only.

Syncthing is also great but may not be what you’re looking for.

Depends on where you want to transfer your files. Do you want to sync your files to a server? Syncthing is perfect for that. SFTP and SCP also work well enough for that. Do you need to send a file to somebody else? Check out croc or portal.

@7_Stipend_Jackal Not really sure what you mean by “like Localshare”. Is that a specific piece of software, or do you just mean sharing files between two devices on a local network via whatever protocol?

I’ve played around with croc a while back just to test, seems okay.

I don’t think the entire service is open source but I really like https://wormhole.app/

One of the GUI versions of Magic Wormhole is the best and easiest way. Here’s my favorite https://rymdport.github.io/

FileZilla.

FTP

SFTP should come with your OS. If you’re on *nix, some fiddling around with usergroups is recommended for security reasons.