SuperTokens is an open source authentication solution offering features like: Different types of login: Email / password, Passwordless (OTP or Magic link based).

SuperTokens.com

The domains are randomly generated, but I can overcome this with:
```
const websiteDomain =
  process.env.NEXT_PUBLIC_VERCEL_ENV === "production"
    ? "https://mydomain.io"
    : process.env.NEXT_PUBLIC_VERCEL_ENV === "preview"
    ? `https://${process.env.NEXT_PUBLIC_VERCEL_URL as string}`
    : "http://localhost:3000"
```