That blog post is a great illustration that most of the complexity/difficulty of a web app is in the hosting and not in the useful code.
clerk is an auth library - and finally one that doesnt require dozens of lines to do things like, i dont know, check if the user is logged in
and wild... you used gemini to process a screenshot to find the website for a 5 letter word library?
Gemini found it via screenshot or context: https://clerk.com/
This is what he used for login on MenuGen: https://karpathy.bearblog.dev/vibe-coding-menugen/