Markdown to HTML Preview

What is Markdown?

Markdown is a lightweight plain-text formatting syntax created by John Gruber in 2004. It lets you write using an easy-to-read, easy-to-write format that converts cleanly to HTML. The idea is that Markdown should be readable as-is, without looking like it has been tagged up with HTML.

Most developers, technical writers, and documentation systems use Markdown today: GitHub, GitLab, Stack Overflow, Notion, Obsidian, Reddit, and hundreds of CMSes all support it.

GitHub Flavored Markdown (GFM)

This tool uses GitHub Flavored Markdown (GFM), a widely adopted superset of the original CommonMark specification. GFM adds:

• Tables: using pipe characters to define columns and rows.
• Task lists: checkboxes with - [ ] and - [x] syntax.
• Strikethrough: wrap text in ~~double tildes~~.
• Fenced code blocks: triple backticks with an optional language hint for syntax highlighting.
• Auto-linking: bare URLs are turned into clickable links.

Markdown quick reference

Security: why HTML is sanitized

Markdown allows embedding raw HTML. While this is powerful, it also means a malicious source could include <script> tags, javascript: links, or inline event handlers like onerror=. This tool runs all output through DOMPurify, an industry-standard DOM sanitizer, before rendering or copying. Dangerous elements and attributes are stripped while all safe, standard HTML is preserved.

Difference between this tool and the full Markdown Editor

This tool is optimized for a single task: paste Markdown, see HTML. It is intentionally minimal. A more capable Markdown Editor is planned for a future release. It will include a toolbar, keyboard shortcuts, file save/load, and syntax highlighting in the editor pane.

Paste from clipboard tips

Copying text from a word processor (Microsoft Word, Google Docs) and pasting it here will produce plain text - the bold, headings, and italics from the word processor will not transfer automatically, because Markdown is plain-text markup. To get formatted output, you need to add the Markdown syntax yourself (e.g., **bold**, # Heading).

Similarly, copying a formatted email and pasting it produces stripped plain text. If you want to convert rich-text HTML to Markdown first, use a dedicated HTML-to-Markdown converter.

Markdown beyond developers

Markdown is no longer just a developer tool - it is now the default writing format in many widely used platforms:

• GitHub / GitLab: READMEs, issues, pull requests, and wikis all render Markdown.
• Notion: supports Markdown shortcuts (type # for a heading, ** for bold).
• Slack: uses a subset of Markdown for bold, italic, code, and strikethrough in messages.
• Discord: supports bold, italic, underline, code blocks, and spoiler tags using Markdown-like syntax.
• Stack Overflow / Reddit: both use CommonMark or Markdown-like formatting in posts.

Learning the basics of Markdown pays dividends across dozens of platforms - it is quickly becoming the universal writing layer of the web.