Tools Viewer

MJML Email Builder – Create & Preview Responsive Emails Online

What Is an MJML Email Builder?

An MJML Email Builder is a browser-based tool for creating responsive email templates with MJML. Instead of setting up a local development environment, you can write or paste MJML code directly into the editor and see the compiled email in the browser.

ToolsViewer's MJML editor online lets you work with MJML components such as mj-body, mj-section, and mj-column while checking the result through a live preview. The MJML preview updates as you work, making it easier to spot spacing, alignment, wrapping, and responsive layout issues.

The MJML email preview can be checked at desktop and mobile widths, with a dark mode simulation available for reviewing colors and contrast. The tool runs the MJML compilation in your browser, so your source code does not need to be uploaded to a server just to generate the preview.

You can also format or minify your MJML source, test merge-tag values with sample JSON data, run email QA checks, and download your source as an .mjml file. The compiled HTML can be copied when you need to move your email template into another email platform.

How to Use the MJML Email Builder

Step 1: Add Your MJML Code
Paste your existing MJML into the editor, choose a template from the gallery, or import an .mjml, .eml, or .mime file.

Step 2: Preview Your Email
Use the MJML email preview to see the compiled result while you edit. Switch between desktop and mobile views to check how your responsive email layout behaves.

Step 3: Format and Test Your Source
Use Format to organize your MJML code or Minify when you need a smaller source file. You can also open Payload and add sample JSON values for {{ variables }} and merge tags.

Step 4: Run Email QA Checks
Open Check Email to review the compiled HTML, plain-text content, headers, links, markup, and other available checks before using the template in production.

Step 5: Download or Copy the Result
Download your source as email-template.mjml or copy the compiled HTML for use with your email service provider.

MJML Email Builder Features

  • Browser-based MJML editor
  • MJML editor online with live compilation
  • Real-time MJML preview
  • Desktop and mobile email previews
  • MJML email preview with dark mode simulation
  • Import .mjml, .eml, and .mime files
  • MJML formatting and minification
  • JSON payload testing for merge tags
  • HTML, text, header, and link checks
  • Email QA tools
  • Mailpit-compatible test sending
  • Download MJML source files
  • Copy compiled HTML
  • No local Node.js setup required

Common Use Cases

Build Responsive Email Templates

Use the MJML Email Builder to create newsletters, promotional emails, transactional messages, onboarding emails, and other responsive email templates without manually managing complicated email tables.

Write MJML Online

The MJML editor online provides a simple workspace for writing and editing MJML directly in your browser. You can make changes to sections, columns, buttons, text, and other email components while viewing the result.

Preview Responsive Emails

Use MJML preview to check your layout at different screen widths. The mobile and desktop views make it easier to identify wrapping, spacing, and alignment problems before deployment.

Test Personalized Email Templates

If your template contains merge tags, add sample JSON through the Payload panel. This lets you see how names, customer information, invoice details, or other dynamic values appear in the email.

Check Email HTML Before Sending

After compiling your MJML, use the available QA checks to review the generated HTML, text version, headers, links, and other email elements before moving the template to your email platform.

Test Dark Mode Layouts

Use the dark mode simulation to review backgrounds, text, buttons, and other visual elements. This provides a quick way to identify contrast or visibility problems in a dark email environment.

Export MJML Source and HTML

Download the original MJML source as email-template.mjml, or copy the compiled HTML when you need to use the finished email with another platform or development workflow.

Supported Formats

The MJML Email Builder supports:

  • MJML code
  • .mjml files
  • .eml files
  • .mime files
  • JSON payloads for merge-tag testing
  • Compiled HTML output
  • email-template.mjml source download

FAQ

Is MJML Email Builder free?
Yes. Tools Viewer tools are free to use in the browser with no account required.
Do I need to create an account to use MJML Email Builder?
No. Open the tool and start working — signup is not required.
Where is MJML compiled?
Compilation runs in your browser with the tool’s MJML runtime. Keep secrets out of any template you paste into an online editor.
Does Download give me compiled HTML?
No. Download saves the MJML source as email-template.mjml. Preview and Send test use the compiled HTML. For HTML screenshots or PDF snapshots, use HTML to PNG, HTML to JPG, or HTML to PDF.
How is this different from HTML Email Builder?
This tool locks the editor to MJML. HTML Email Builder locks the editor to HTML. Both share preview, checks, Payload, and Send test patterns.
Can I download compiled HTML directly from the builder?
The primary Download action exports the clean MJML source code (email-template.mjml) so you keep your responsive source of truth intact. To use the compiled table-based HTML in your ESP, preview your template and copy the compiled code directly from the preview or check workflows.