[Feature Request] Authentication for own server instances

[MrCybertux]

When setting up own servers there is no way right now to keep them private sice there is no way of securing the instance.
"Hiding" behind a "secret" URI is not an option since after discovering the server with for example nmap you just need to brute force your way in.
IP whitelisting or VPNs are not always practical in an environment with a lot of mobile users.
In case you have your own rules written for the server they could be leaked via trial and error too and this is a massive privacy issue.

There has been the proposal for basic auth which was denied #4308 because of external factors limiting the abilities of browser add-ons if I got that right

If an HTTP auth is not supported, maybe there is a way to implement an API key or User and Password or an Oauth2 etc.

In some way or form, the Browser add-ons can do that already, since you can log in on the languagetool.org server with your account.

[h-2]

Offering a 50€ bounty for this! Maybe someone else would like to add to that?

edit: Specifically: A somewhat secure way to password-protect (or user+password) an instance of the LanguageTool server running on my own hardware, so that I can connect my family's computers to that and not have to waste RAM on each device by running their own.