Sidemail - The simplest way to send transactional emails. Sidemail makes sending transactional emails trivial, it's perfect for side projects, MVPs or the next big thing.
Templates by Email Monster - Hundreds of free, responsive email templates. Pick and edit.
Semplates.io - Create, edit and manage all your email templates on AWS SES with ease.
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.
Mailook - Identify & fix your email deliverability issues for free 👀
MJML - The open source framework for responsive emails