Auth solutions for ASP .NET core web api?

Hey peeps 👋

I’m a front end focused full stack dev (I spend about 80 percent of my time on front end, 20 percent back end, I’ve been a dev for about 2 and a half years) and I’ve never set up an auth service before… but figured it would be handy to make this a micro service that in future could be used with a number of apps I might build, rather than tied to the boiler plate of an individual service..

What’s your go to auth solution for your ASP.NET 6.0 core web api?

Ps I don’t really want to use identity server as it costs a bomb and I’m just small fry.

Cheers