Markdown, GFM extras, and why safe rendering matters
Markdown won because it is readable before it is rendered. A heading is a hash, a list is dashes, emphasis is asterisks — you can skim the raw source of a README and understand it without ever opening a preview. But the moment you write anything real, plain Markdown runs out of road: there are no tables, no task lists, no strikethrough. GitHub-flavored Markdown (GFM) filled exactly those gaps, and it is the dialect your issues, pull requests and READMEs already use.
The part nobody thinks about until it bites them is rendering safety. Markdown gets pasted from everywhere — tickets, chat, emails — and a naive renderer that passes raw HTML through will happily execute a smuggled script tag, and a naive link handler will turn a javascript: URL into a one-click XSS. A trustworthy live markdown renderer neutralizes both: raw HTML displays as inert text, and dangerous URLs are stripped before they ever reach the page.
Open the free Markdown Preview — no signup, runs entirely in your browser.
How to use it
- Type or paste Markdown into the editor pane — or hit Sample to load a demo document with headings, a table, a task list and a code block.
- Read the rendered output in the preview pane; on wide screens the two panes scroll in proportional sync.
- On a phone, flip between the Edit and Preview tabs — the layout collapses to a single focused view.
- Hit Copy HTML to export the rendered markup, wrapper styling classes included, ready to paste into a page or CMS.
Why this one
- Full GFM support: pipe tables, task lists with real checkboxes, strikethrough and autolinks all render correctly.
- XSS-safe by construction — raw HTML is never executed and javascript: URLs are neutralized by the renderer's sanitizer.
- External links always open in a new tab with rel=noopener noreferrer, so the preview can't be used for tab-nabbing.
- Live word, character and line counts in the footer make it double as a quick writing-length checker.
Frequently asked questions
Does the preview render raw HTML embedded in my Markdown?
No — and that is deliberate. Raw HTML in the source is displayed as plain text, so a pasted script or iframe tag is inert and visible instead of executed. This mirrors how GitHub sanitizes comments and keeps pasted content from untrusted sources safe to preview.
What does the Copy HTML button actually copy?
The inner HTML of the preview container, exactly as rendered. It carries the preview wrapper's utility classes, which is handy if your site uses the same styling and easy to strip if it does not. When rich clipboard writes are unavailable it falls back to plain text.
Which Markdown dialect is supported?
GitHub-flavored Markdown via remark-gfm: everything from standard CommonMark plus tables, task lists, strikethrough and autolinked URLs. Footnotes and other non-GFM extensions are not rendered.
Is my document uploaded anywhere when I preview it?
No. Parsing and rendering run entirely in your browser, and clearing the editor removes the text. Nothing is sent to a server, which also means the preview works fully offline once the page has loaded.