Supabase login or magic link sends users to localhost

What it means

After signing in, users land on localhost:3000 (or another dev address) and see an error page. Supabase is sending them to the address in its settings, which is still your development one.

Why AI tools cause it

Supabase's Site URL defaults to localhost while you build, and AI tools rarely remind you to change it when you go live.

The fix

1. In Supabase, open Authentication → URL Configuration.
2. Set Site URL to your live address, e.g. https://yourapp.com.
3. Under Redirect URLs, add your live address and keep http://localhost:3000/** for local testing.
4. In your code, pass emailRedirectTo (magic links) or redirectTo (OAuth) using your site's current address rather than a hard-coded localhost.

Paste this into your AI

After deploying, Supabase auth redirects users to localhost. Find every place this project sets a redirect URL for sign-in, sign-up, magic links or password reset, and change them to use the current site's origin. Then tell me exactly what to set as Site URL and Redirect URLs in Supabase.

Still broken?

Old magic-link emails still contain the old address. Request a new link after changing the settings.