MJML

Overview

MJML is a code-first tool for building responsive email layouts, best suited to developers and teams comfortable working with markup. Its component system and free rendering options make it a practical way to produce email HTML; it does not send the finished email.

Instead of authoring the output’s nested tables and inline CSS directly, you write MJML and let its engine generate that HTML. The result is designed for popular email clients, including Outlook. Reusable components give projects a consistent foundation, and custom components allow teams to extend it. MJML has been open source under the MIT license since its founding in 2015.

The boundary is clear: MJML creates and renders templates, but delivery requires an email service provider or sending directly from a shell. Readers seeking a visual design workflow or an end-to-end email service should look elsewhere.

Key features

• Responsive rendering: The engine compiles MJML into email HTML using nested tables and inline CSS. That abstraction can reduce the burden of responsive email coding, particularly for developers targeting clients such as Outlook.
• Reusable and extensible components: Built-in components provide repeatable layout elements, while custom components let teams adapt the markup system to their needs. This favors structured, code-managed work over designing each email visually.
• Multiple authoring routes: A free online editor lets users write and render MJML in a browser. For local work, MJML installs through npm on macOS, Linux, and Windows; plugins are available for Visual Studio Code and Sublime Text, alongside a desktop app.
• CLI and API: The command line can compile files, watch for changes, and write generated HTML to a chosen file. The free REST API renders MJML as well. Each API account receives one Application ID and two API keys, with public and secret keys intended respectively for browser and back-end use.
• Controlled includes: Includes are ignored by default. If enabled, their paths are restricted to approved roots with canonical boundary checks, a useful guardrail for projects that rely on included files.
• Integrations and community: The documented ecosystem includes Mailjet, Parcel, IntelliJ IDEA, Gradle, Neos CMS, and Easy-email. Users can contact the team by email or participate through Slack and GitHub.
• Email-client constraint: The mj-button component is not fully clickable because of email-client support. That limitation matters for calls to action where the whole button area is expected to behave as a link.

Pricing

MJML’s Free plan costs 0.00 USD per free and includes use of its REST API at no charge. The online editor is also free. There are no paid tiers described, so the appeal is straightforward for developers who want a no-cost markup-to-HTML workflow rather than a packaged visual design service.

The trade-off is scope, not a stated quota: MJML renders HTML but leaves sending to a separate provider or shell workflow. Teams that need delivery, visual collaboration, or other production capabilities should assess a separate service rather than expect MJML to cover them.

Platforms

MJML spans API, browser, extension, Linux, macOS, and Windows use. The browser editor suits quick authoring without local installation; npm, CLI, and editor plugins better fit developers incorporating markup into a local workflow. The API offers a way to render MJML from an application, but it does not remove the need to arrange email delivery.

Who it's for

MJML is a strong fit for developers, agencies, and product teams that want reusable, code-first email layouts and control over how rendered HTML enters their delivery pipeline. Its free editor, CLI, and API let people choose between browser-based work, local compilation, and programmatic rendering.

It is a weaker fit for people who want to compose campaigns visually without markup, or who expect the same product to manage sending. The button clickability caveat is also relevant when a design depends on a fully clickable button component.

Pros and cons

• Pro — Free across key workflows: The online editor and REST API are free, and the Free plan is priced at 0.00 USD per free, lowering the cost of adopting a markup-based renderer.
• Pro — One markup workflow across tools: Browser editor, npm installation, CLI, editor plugins, desktop app, and API support different development habits without changing MJML’s rendering purpose.
• Pro — Extensible structure: Reusable components and custom component support help teams establish repeatable layouts rather than repeatedly building output HTML from scratch.
• Con — Not a sending platform: Rendered HTML must be delivered through another provider or a shell-based process, adding a separate step and service choice.
• Con — Requires a code-first approach: Its markup language and developer tooling are less suited to readers looking for a visual email builder.
• Con — Button limitation: The mj-button component is not fully clickable in supported email-client conditions, which can constrain some calls to action.

Alternatives

For a wider range of options, browse Email Template Software or Email Design Software.

• Blocks Edit is a web-based freemium alternative with a free trial and yearly plans including Collaborate at 20.00 USD per year with 250 GB storage and a 5-user plan at 99.00 USD per year.
• Unitpost is a web and API freemium alternative whose Free plan includes monthly email, daily sending, contact, domain, webhook, and hosted-image limits.
• Dragble is a web, API, and self-hosted freemium option with a free trial; its Free plan includes 3 projects, 10 GB storage, 10 core content blocks, and Dragble branding.
• MailEditor is a web and extension freemium alternative with API support; its Starter plan is 9.00 USD per month and includes export, member, template, storage, and AI-template limits.
• Serious Email Studio is a web-based freemium option; its Free plan allows 1 user, 3 projects, 10 templates, and responsive previews.
• Stripo is a web and API freemium alternative with a free plan capped at 2 members, 4 monthly exports, 5 daily test emails, and 10 stored emails.
• Unlayer offers web, API, and self-hosted access, with a free trial and a forever-free plan covering email, page, popup, and document builders without a credit card.
• Postcards is a web and extension freemium alternative with API support; its Start plan includes 10 template projects, 5 monthly exports, no monthly AI credits, 10 daily test emails, and unlimited teammates.

Verdict

Choose MJML if you want a free, extensible way to turn code-managed email layouts into responsive HTML and are prepared to handle delivery separately. Its strongest case is the combination of reusable components with browser, local, CLI, and API rendering routes. Look elsewhere if you need a visual-first authoring experience, integrated sending, or a fully clickable mj-button.