Markdown Editor & Preview

What is GitHub Flavored Markdown (GFM)?

CommonMark is the baseline: standard markdown with headings, lists, bold, italic, links, images, code blocks, and blockquotes. GitHub Flavored Markdown extends it with three powerful additions:

• Tables — organize data in rows and columns
• Task lists — checkboxes for to-do items and progress tracking
• Strikethrough — mark text as deleted or superseded

This tool renders GFM, so all three features work here. But GFM is GitHub's extension, not a universal standard — if you move markdown to another platform, these features may not render the same way.

Why is HTML sanitisation important?

When you convert markdown to HTML, the output is just text — until a browser renders it. Raw HTML can contain scripts, event handlers, and other code that runs when the page loads. This is an XSS (cross-site scripting) vulnerability if the markdown input is not fully trusted.

This tool uses DOMPurify to strip any dangerous elements before display. Unsafe tags, attributes, and event handlers are removed. The preview you see is safe to read, and the HTML you copy is safe to paste. However, sanitisation also removes some legitimate formatting — for example, inline styles are stripped for safety.

For trusted content: If you control the markdown source (you wrote it, or it came from your own system), sanitisation is extra caution. For untrusted content: (pasted from the internet, user-generated) sanitisation is essential — never render untrusted HTML without it.