Open **Newsletter Analytics** and click **Add List**. Enter the API key. Mailchimp and several other platforms also ask you to pick the audience or list. The app checks the key, then pulls subscriber count, open rate, and click rate.

Supported platforms: Mailchimp, Kit, MailerLite, Beehiiv, EmailOctopus, Sendy, SendFox, Flodesk, and Brevo. A Flodesk segment counts as the list. Sendy reports subscriber count only.