Web
A truly multilingual ASP.NET Core site
A switcher that stores language in a cookie is handy for returning users and terrible for SEO. Search engines and AIs see one URL.
What actually works
Culture prefix (/es, /en, /de-ch), hreflang, canonical, sitemap with all six variants, and native copy — not a machine translation pasted on top.
Swiss German spelling
de-CH is not a whim: it is another spelling (ss, Grösse, massgeschneidert). Treating it as plain German loses trust in CH.
On the corporate plan (€2,500) this is included for up to 6 languages. It is the same approach this site uses.
Short questions
Does Google understand de-CH?
Yes, if the URL and hreflang are de-CH and html lang too. That is why we do not use lang=de only.
Can I start with one language?
Yes. The architecture is ready to add cultures without rebuilding the site.