How to test Google One-tap on localhost? Getting a 403

Question

The banner at the top of https://developers.google.com/identity/one-tap/web/overview says that while we must be on the whitelist to deploy this on a production site, we can test it out on localhost. However, when I try this, I still get a 403 Forbidden when including the embed script:

<script defer src="https://smartlock.google.com/client"></script>

I made sure that http://localhost:8000 is on my list of "Authorized JavaScript origins" in my OAuth Credential.

Is it possible to test out Google One-tap on localhost?

Answer 1

In your "Authorized JavaScript origins", do not include the port (even though the help text says "If you're using a nonstandard port, you must include it in the origin URI."). Use http://localhost, not http://localhost:8000.

Answer 2

HTTP403 means Forbidden - which is being covered in the Common Issues ...

window.location.origin does not have any port, but only protocol & hostname.