Try Inboxless

A practice code field: no account, nothing is submitted.

1. Install Inboxless and connect at least one Gmail account.
2. From a different email account, send that Gmail a message with the subject Your verification code and the text Your verification code is 482913. Any 4–8 digit code works.
3. Keep this page open. Within a few seconds Inboxless shows the code, copies it and opens its popup.
4. Because the email wasn’t sent by codecatch.site, Inboxless won’t type it in by itself. It asks first; that’s the phishing protection. Click Fill on the card, or Paste into page in the popup.