MJML vs Open Email

MJML is a markup language for building responsive email layouts. Its engine converts MJML into email HTML made with nested tables and inline CSS, with responsive behavior for popular email clients, including Outlook. Reusable, extensible components provide a starting point, and users can create their own components. MJML is open source under the MIT license and free to use. Its online editor supports writing and rendering MJML, and its free REST API renders markup into responsive HTML. The command-line interface can compile files, watch for changes, and save generated HTML to a chosen file. Local installation is available through npm on macOS, Linux, and Windows; plugins are available for Visual Studio Code and Sublime Text, alongside a desktop app. API accounts receive an Application ID and two API keys, with public and secret keys intended for browser and back-end use. Includes are ignored by default, and enabled include paths are restricted to approved roots. Once the HTML is rendered, users must send it through an email service provider or directly from a shell. The mj-button component is not fully clickable because of email-client support.

Open Email has no write-up on Specifiction yet; its figures are above.