MJML vs Postcards

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.

Postcards is a visual drag-and-drop builder for responsive marketing emails made from blocks and templates. Users can export clean HTML or send designs to listed email platforms, including Mailchimp, HubSpot, Klaviyo, SendGrid, Brevo, Constant Contact, and Zoho; export limits depend on the plan. Existing HTML emails can be imported and edited on paid plans. The AI Suite can generate templates from prompts and assist with editing, restyling, restructuring, translation, and design analysis. Shared workspaces, real-time collaboration, comments, and teammate roles support team work. Paid plans include Email Client Preview for checking Gmail, Outlook, Apple Mail, and Yahoo on mobile and desktop. The builder runs in a browser and requires an internet connection, though exported files can be opened and edited offline. Access is through the maker's hosted app link. The free Start plan costs nothing and includes 10 template projects, five monthly exports, 0 AI credits per month, 10 test emails daily, and unlimited teammates. Plus costs $16 a month; Pro costs $24 a month. The maker says user projects and content remain theirs and are not used to train AI models.