Spark Mail - Spark helps you take your inbox under control. Instantly see what’s important and quickly clean up the rest. Spark for Teams allows you to create, discuss, and share email with your colleagues

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.

Email Testing By Inbox Pirates - Preview, Analyze & Test emails with one click.

MJML - The open source framework for responsive emails

iMailair - We all know that email is broken.

Unlayer - Embeddable email editor and page builder for SaaS and CRMs