Convertkit is an email marketing software (or an email service provider) that is specifically built around the needs of bloggers, writers, podcasters, course creators, YouTubers, content creators and others who are working to build an audience.
The platform helps you to increase your email subscriber list and automate email marketing with drag-n-drop email sequences, workflow automation rules, landing page templates, custom opt-in forms, and more.
It has all the basic functionality you expect from an email marketing software.
Autoresponders (email sequences) Newsletters (broadcasts) Optin forms to build your list
It has segmentation options so you have multiple lists and trigger different responses based on people's engagement with your email.
I have personally used ConvertKit and it is a great software to use. I have been on their free plan, and that's mainly what I use (limit of 1000 subscribers). I am not a paying subscriber.
I did a video review on ConvertKit showing you the inside. You can check it out here.