Google Chrome, Firefox, and Thunderbird extension that lets you write email in Markdown and render it before sending.
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Markdown Here logo Markdown Here

Get it for Chrome
Get it for Firefox, Thunderbird, and Postbox

Markdown Here is a Google Chrome, Firefox, and Thunderbird extension that lets you write email in Markdown and render them before sending. It also supports syntax highlighting (just specify the language in a fenced code block).

Writing email with code in it is pretty tedious. Writing Markdown with code in it is easy. I found myself writing email in Markdown in the Github in-browser editor, then copying the preview into email. This is a pretty absurd workflow, so I decided create a tool to write and render Markdown right in the email.

To discover what can be done with Markdown in Markdown Here, check out the Markdown Cheatsheet.

*: And Google Groups posts, and Wordpress posts, and Evernote notes, and Postbox! See details.
*: And TeX mathematical formulae!

screenshot of conversion

Table of Contents

Installation Instructions
Usage Instructions
Notes and Miscellaneous
Building the Extension Bundles
Next Steps, Credits, Feedback, License

Installation Instructions


Chrome Web Store

Go to the Chrome Web Store page for Markdown Here and install normally.

After installing, make sure to reload your webmail or restart Chrome!


  1. Clone this repo.
  2. In Chrome, open the Extensions settings. (Wrench button, Tools, Extensions.)
  3. On the Extensions settings page, click the "Developer Mode" checkbox.
  4. Click the now-visible "Load unpacked extension…" button. Navigate to the directory where you cloned the repo, then the src directory under that.
  5. The Markdown Here extension should now be visible in your extensions list.
  6. Reload your webmail page (and maybe application) before trying to convert an email.

Firefox and Thunderbird

Mozilla Add-ons site

Go to the Firefox Add-ons page for Markdown Here and install normally.

Or go to the "Tools > Add-ons" menu and then search for "Markdown Here".

After installing, make sure to restart Firefox/Thunderbird!

Note: It takes up to a month for Mozilla to approve changes to the Firefox/Thunderbird extension, so updates (features, fixes) will lag behind what is shown here. You can manually choose to install the newest version before it's reviewed from the list of versions:


  1. Clone this repo.
  2. Follow the instructions in the MDN "Setting up an extension development environment" article.

Usage Instructions

Install it, and then…

  1. In Chrome or Firefox, log into your Gmail, Hotmail, or Yahoo account and start a new email. In Thunderbird, start a new message.

  2. Make sure you're using the rich editor.

    • In Gmail, click the "Rich formatting" link, if it's visible.
    • In Thunderbird, make sure "Compose messages in HTML format" is enabled in your "Account Settings", "Composition & Addressing" pane.
  3. Compose an email in Markdown. For example:

    **Hello** `world`.
    alert('Hello syntax highlighting.');
  4. Right-click in the compose box and choose the "Markdown Toggle" item from the context menu.

  5. You should see your email rendered correctly from Markdown into rich HTML.

  6. Send your awesome email to everyone you know. It will appear to them the same way it looks to you.

Revert to Markdown

After rendering your Markdown to pretty HTML, you can still get back to your original Markdown. Just right-click anywhere in the newly rendered Markdown and click "Markdown Toggle" -- your email compose body will change back to the Markdown you had written.

Note that any changes you make to the pretty HTML will be lost when you revert to Markdown.

In Gmail, you can also use the browser's Undo command (ctrl+z / cmd+z, or from the Edit menu). Be warned that you might also lose the last few characters you entered.


In Gmail, Thunderbird, and Google Groups, you can use "Markdown Toggle" normally: just write your reply (top, bottom, inline, wherever) and then convert. The original email that you're replying to will be left alone. (Technically: Existing blockquote blocks will be left intact.)

In Hotmail and Yahoo (which don't put the original in a blockquote), and optionally in Gmail, Thunderbird, and Google Groups, you can ensure that only the part of the reply that you wrote gets converted by selecting what you want to convert and then clicking "Markdown Toggle" -- see the next section.

Selection/Piecemeal Conversion

Sometimes you don't want to convert the entire email; sometimes your email isn't entirely Markdown. To convert only part of the email, select the text (with your mouse or keyboard), right-click on it, and click the "Markdown Toggle" menu item. Your selection is magically rendered into pretty HTML.

To revert back to Markdown, just put your cursor anywhere in the block of converted text, right click, and click the "Markdown Toggle" menu item again. Now it's magically back to the original Markdown.

screenshot of selection conversion

Things to know about converting/reverting a selection

  • If you select only part of a block of text, only that text will be converted. The converted block will be wrapped in a paragraph element, so the original line will be broken up. You probably don't want to ever do this.

  • You can select and revert multiple converted blocks at the same time. One upshot of this is that you can select your entire email, click "Markdown Toggle", and all portions of it that you had converted will be reverted.

  • If you don't have anything selected when you click "Markdown Toggle", Markdown Here will check if there are converted blocks anywhere in the message and revert them. If there no converted blocks are found, it will convert the entire email.


The Markdown Here Options page can be accessed via the Chrome, Firefox, or Thunderbird extensions list. The available options include:

  • Styling modifications for the rendered Markdown.
  • Syntax highlighting theme selection and modification.
  • TeX math formulae processing enabling and customization.

For Chrome and Firefox, any changes made in the Markdown Here Options are automatically synchronized between your other installations of that browser (if you have the sync feature enabled in the browser).

screenshot of options


Here are some common problems that people run into.

Chrome/Firefox/Thunderbird: I just installed Markdown Here and the context menu item isn't showing up.
Make sure you restarted Firefox or Thunderbird, and either restarted Chrome or reloaded your webmail page.


Short answer: Gmail and Thunderbird are great. More info about some clients can be found in the wiki.

Compose Send Receive Notes
Hotmail Paragraphs don't appear spaced correctly. (But they do appear spaced correctly when viewed by recipients.) Email from received from Yahoo does not display with properly separated paragraphs. (Hotmail strips styling off <p> and <div> tags, and Yahoo uses the latter for paragraphs.)

Code blocks with very dark backgrounds aren't displayed correctly.

No reply exclusion.
Yahoo No reply exclusion.
Google Groups Rendered version doesn't show in digest email. But that's probably true of manually-rich-edited posts as well.
Wordpress Editor not exactly WYSIWYG, but Preview is accurate See the Compatibility wiki page for full details and tips
Evernote (web interface) Seems to strip newlines from <pre> blocks, which breaks display of code.
Postbox Inserts newlines in raw email, which can mess up code blocks. No options page. No reply exclusion.


How Markdown Here behaves when composing an email. E.g., if rendering and reverting looks correct, styling is good, etc.


Negative effect that may occur when sending a rendered email from this email client. E.g., stripped tags and styles.


How well this email client displays rendered email that it receives (assuming the sender is perfect).

Notes and Miscellaneous

  • Markdown Here uses Github Flavored Markdown.

    • ...with limitations. Please see the Issues for details, but here are some examples:
      • No support for GFM special links: issue #11
      • No support for GFM-style line breaks: issue #12
      • No support for GFM-style tables: issue #13
  • Available languages for syntax highlighting (and the way they should be written in the fenced code block) can be seen on the highlight.js demo page.

  • Images embedded inline in your Markdown will be retained when you "Markdown Toggle". Gmail allows you to put images inline in your email -- this can be much easier than referencing an external image.

  • Email signatures are automatically excluded from conversion. Specifically, anything after the semi-standard '-- ' (note the trailing space) is left alone.

    • Note that Hotmail and Yahoo do not automatically add the '-- ' to signatures, so you have to add it yourself.
  • The "Markdown Toggle" menu item shows up for more element types than it can correctly render. This is intended to help people realize that they're not using a rich editor. Otherwise they just don't see the menu item and don't know why.

  • Styling:

    • The use of browser-specific styles (-moz-, -webkit-) should be avoided. If used, they may not render correctly for people reading the email in a different browser from the one where the email was sent.

Building the Extension Bundles

"Building" is really just zipping. Create all archives relative to the src directory.

An important preparatory step is to remove any system-generated hidden files that shouldn't be included in the release file (like Windows' desktop.ini and OS X's .DS_Store, etc.). This shell command will delete those unwanted files:

find . -name "desktop.ini" -or -name ".*" -and -not -name ".git*" -print0 | xargs -0 rm -rf

Chrome extension

Create a file with a .zip extension containing these files and directories:


Firefox/Thunderbird extension

Create a file with a .xpi extension containing these files and directories:


Next Steps

  • Figure out how to prevent users from losing modifications to the rendered version when they revert.

    • Prompted by this Reddit comment.
    • Maybe add an option to make rendered mode read-only. If a user edits the rendered text and then reverts, they lose their changes, which is pretty bad. Better to not let the user make changes at all (optionally).
      • Is it possible to do that? In Thunderbird as well?
    • Maybe convert the HTML back to Markdown. (Like, actually convert it -- don't just use the stashed original Markdown.)
  • Test cases.

  • Add a configurable hotkey.

  • Add user option to specify Markdown dialect?

  • Briefly highlight rendered and reverted blocks/ranges.

  • Add a visual cue as to what action took place. Sometimes converts and reverts may be a little surprising if the user's selection is off. And sometimes their viewport won't show the entirety of what change occurred.

  • When Thunderbird sends and displays, it leaves the md-data-original attribute (which contains the original Markdown) intact. We could provide the user the ability to extract this. (I know at least one person who wants this.)

  • Internationalization

  • Fix inconsistent behaviour: Sometimes a converted/reverted block ends up selected, and sometimes not.

  • Make email signature conversion exclusion optional. (Maybe some people will make a special one to convert.)


Markdown Here was coded on the shoulders of giants.

Other stuff not used, but to keep an eye on


All bugs, feature requests, pull requests, feedback, etc., are welcome.