Web

Native implementation

Web loads Google Identity Services on demand:

https://accounts.google.com/gsi/client

It initializes GIS with:

{
  client_id: webClientId,
  nonce,
  auto_select: web.autoSelect,
  use_fedcm_for_prompt: web.useFedCm
}

Authorized JavaScript origins

Google checks the exact origin of the page. These are different origins:

http://localhost:8081
http://127.0.0.1:8081
http://localhost:8082

Add every origin you use to the OAuth Web client's Authorized JavaScript origins.

FedCM

FedCM prompt support is enabled by default:

web: {
  useFedCm: true
}

You can turn it off if you need to debug older GIS behavior:

web: {
  useFedCm: false
}

Auto-select

web: {
  autoSelect: true
}

Allows Google Identity Services to auto-select an account when eligible.

unregistered_origin

This means the current page origin is not authorized for the Web client ID you passed as webClientId.

Check:

• The app is using the same Web client ID shown in Google Cloud Console.
• The exact browser origin is listed in Authorized JavaScript origins.
• You clicked Save in Google Cloud Console.
• You waited for Google configuration propagation.