I frequently use `python -m http.server` on my LAN.
And if I can't be bothered to setup Python on the source host, or there are network complications, running uploadserver[1] on the destination host works great.
I'm wary of all these fancy tools with "magic" in their name, that rely on external relay servers. Even if they don't, I'm quite fond of the simplicity of plain old HTTP. I don't need anything more sophisticated, and in most cases, not even encryption.
netcat/socat would be another solution, but they're not as ubiquitous as Python and HTTP. And I can never remember the command incantations ':D
You first start one server on a desktop/laptop which has the software, and then any client (Android, iOS, PlayStation, Kindle, etc) with a web browser (no need to install any client software) can upload or download files from the web GUI.
You can download prebuilt binaries for x86-64 Linux, Windows, or Mac OS (sorry, no prebuilt binaries for Apple Silicon, but they could be added if there is sufficient demand) from https://github.com/akovacs/uploadserver/releases/ or compile from source using a nightly rust toolchain if you prefer.
Compared to cloud services or `python -m http.server 8000`, this is extremely fast since the server is written in rust, it is fairly simple (compiled and stripped binary is typically less than 3MB), it sends everything over local LAN, it seems to handle large files (over 4GB) fairly well, and you only need to install the software on one machine.
I have used such apps before, but it seems they have gone unmaintained and don't work anymore.