Templates by Email Monster - Hundreds of free, responsive email templates. Pick and edit.
HubSpot - Grow Better With HubSpot: Software that's powerful, not overpowering. Seamlessly connect your data, teams, and customers on one CRM platform that grows with your business.
MJML - The open source framework for responsive emails
MailChimp - MailChimp is the best way to design, send, and share email newsletters.
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.
Marketo - Marketo's powerful marketing automation software helps marketers master the art & science of digital marketing to engage customers and prospects.