Signup using Lichess

I very much would like to place a "Continue using Lichess" button on my website where people would click a button and login to my site using their Lichess account.

My use case is that I want people to configure their Lichess account on my site and I want to validate if they really are who they claim to be.

What possibilities are there to realize this?

Anyone?

why not simply contribute to the lichess codebase?

I don't think Lichess is an authentication service provider.

Yes.

Lichess Authentication would be really helpfull for sites like lichess4545.com. They are offering long time tournaments and connecting with lichess would be pretty nice improvement.