Stripo - Stripo is an all-in-one email design platform. We enable our clients to build emails of any complexity, including interactive AMP emails, really fast and easy.
Templates by Email Monster - Hundreds of free, responsive email templates. Pick and edit.
MailDeveloper - Advanced editor for responsive HTML emails
MailerLite - Affordable Email Marketing Software. Get all features (Segmentation, Automation, A/B testing) for up to 1,000 subscribers & send unlimited emails for free!
MJML - The open source framework for responsive emails
BeeFree - BeeFree is an all-in-one solution that works anywhere you are.