Please review the separate help page on why you need a Pinterest application.
IMPORTANT: If you have an existing Pinterest application that you previously used in the legacy version of our service, then use that Pinterest application. The same Pinterest application works in both the legacy and the new version of the service. Just edit your Pinterest application at Pinterest.com and change the redirect URI to the one listed in Step 11 below.
To create a Mastodon application, please follow the steps below:
https://www.socialoomph.com/pinterest/callback/in the Redirect URIs field, and press Enter to save the URL.