Write Markdown with a formatting bar and read it back rendered as you type, side by side or one at a time, in GitHub, CommonMark or original flavour.
How it works
The preview is redrawn a moment after you stop typing. Split, Editor and Preview decide which halves are showing, and the hidden half stays loaded, so the undo history survives a switch. Open file, or dropping a file on the editor, replaces the whole document with a UTF-8 text file of up to 1 MB, as one step that Ctrl+Z takes back.
The formatting bar wraps the selection, or the word under the caret, in bold, italic, strikethrough or inline code, and a second press takes the markers off. The heading, quote and list buttons apply to every selected line. Ctrl+B, Ctrl+I, Ctrl+E and Ctrl+K (Cmd on a Mac) give bold, italic, code and a link.
The Flavour menu sets how the text is read:
| Flavour | Tables, strikethrough, task lists, bare URLs as links | A single newline | Fenced code |
|---|---|---|---|
| GitHub Flavored (default) | yes | a space | yes |
| GitHub Flavored, Hard Breaks | yes | a line break | yes |
| CommonMark | no | a space | yes |
| Original Markdown | no | a space | no |
Raw HTML is allowed, as Markdown intends, but what the parser produces goes through DOMPurify before it is shown: scripts, on… attributes, javascript: links, stylesheets, style attributes and forms are removed, and links open in a new tab. That matters because the document is kept in the page's address, so a shared link shows somebody else's text.
Download saves the Markdown itself, the preview as a standalone HTML page with its styles inside it, or a PDF or Word document written in the tab. Each file is named after the first heading: # Release notes: v2.0 becomes release-notes-v2-0.md.
Examples
Where a heading and a list begin
#Notes
Shopping:
- eggs
- milkIn GitHub Flavored and CommonMark:
<p>#Notes
Shopping:</p>
<ul>
<li>eggs</li>
<li>milk</li>
</ul>In Original Markdown:
<h1>Notes</h1>
<p>Shopping:
- eggs
- milk</p>CommonMark wants a space after the # but lets a list interrupt a paragraph. The original rules were the other way round on both counts.
A table and a strikethrough
| Key | Value |
| --- | --- |
| a | 1 |
~~old~~ newGitHub Flavored draws a table with a Key and a Value column and strikes through old. CommonMark and Original Markdown leave the table as one paragraph of pipes and print the tildes as they are. The | --- | row is required: without it even GitHub Flavored sees a paragraph.
What the sanitiser takes out
<b onclick="x()">hi</b> <script>alert(1)</script> [link](javascript:alert(1))<p><b>hi</b> <a>link</a></p>The bold survives; the handler, the script and the link's address do not.
Common problems
Line breaks disappear
A single newline inside a paragraph is a space in every flavour but GitHub Flavored, Hard Breaks. To break a line anywhere, end it with two spaces or a backslash; one, two spaces, a newline and two puts the words on separate lines in all four flavours.
The next line joins the quote or the list item
A line straight after a quoted line or a list item carries on that block even without a > or an indent. This is called lazy continuation and every flavour does it: > quoted line followed by continues here is one quote. Leave a blank line to end the block.
A code fence turns into inline code
Original Markdown has no fenced code blocks, so three backticks become an inline code span that runs the lines together. Indent the code by four spaces after a blank line, which works in every flavour.
A picture is missing from the PDF or the Word document
The preview asks the browser to show each picture, but the PDF and Word writers have to fetch it. A picture that is not PNG, JPEG, SVG or, for Word, GIF, whose host does not allow cross-origin reads, or that takes longer than five seconds is replaced by its alt text in italics.
Frequently asked questions
Which flavour should I pick?
GitHub Flavored for a README or anything else GitHub will render; it is the default. CommonMark for a tool that follows the plain specification without GitHub's additions. Original Markdown only to check how John Gruber's 2004 rules treat a document.
Can I use HTML inside the Markdown?
Yes. Elements such as details, kbd and sub render in the preview and in the HTML download, after DOMPurify has removed scripts, event handlers and javascript: links. An iframe, style or form is removed as well.
How are the PDF and the Word document made?
Both are written in the tab from the same parser and flavour as the preview, with no print dialog. The PDF is set by pdfmake in embedded Roboto, as selectable text. The Word document uses Word's own heading, list and table styles, so it stays editable. Inline HTML tags such as kbd are dropped and their text kept; a block of HTML is left out.
Why won't my file open?
The page opens UTF-8 text up to 1 MB. A file that is not valid UTF-8, such as Windows-1252 text with accented letters or a picture dropped by mistake, is refused with a message, and the current document is left as it was. The hex viewer shows which bytes are to blame.