A Markdown preview tool turns Markdown text into formatted HTML as you type, so you can see exactly how your headings, lists, links, and code blocks will look before you publish. Type or paste Markdown on the left and the rendered result appears live on the right. When it looks right, use Copy as HTML to grab the underlying markup. Everything runs in your browser, and nothing you type is sent anywhere.
What is Markdown?
Markdown is a lightweight plain-text formatting syntax created to be easy to read and write. Instead of clicking toolbar buttons, you add small symbols to your text: a # for a heading, asterisks for bold or italic, hyphens for a bullet list. Those symbols are then converted into HTML for display. Because the source stays readable even before conversion, Markdown has become the default for README files, documentation, static-site content, chat apps, issue trackers, and note-taking tools.
What this tool renders
This previewer implements a practical subset of GitHub-Flavored Markdown (GFM) — the parts people actually use most days:
- Headings —
# Titlethrough###### Title. - Emphasis —
**bold**,*italic*, and`inline code`. - Lists — ordered (
1.) and unordered (-,*,+), with one level of nesting. - Code fences — triple-backtick blocks with an optional language label.
- Links and images —
[text](url)and, with unsafe URL schemes stripped. - Blockquotes, tables with column alignment, and horizontal rules.
A worked example
Given this Markdown source:
# Release notes
- Fixed the **login** bug
- Added a `--verbose` flag
See the [changelog](/changelog) for details.the tool produces a heading, a two-item bullet list with bold and inline-code emphasis, and a paragraph containing a link — exactly what a reader would see once the page is published. Toggle to Copy as HTML and you get the clean <h1>, <ul>, and <a> markup ready to paste elsewhere.
Safety: why raw HTML cannot run here
Every angle bracket in your source is escaped before any Markdown formatting is applied. That ordering matters: it means a pasted <script> tag, an onerror attribute, or any other embedded HTML is displayed as literal text and never becomes live markup. On top of that, link and image URLs are checked, so common attack vectors such as javascript: and data: URLs are rejected and shown as plain text instead of being turned into clickable elements. The only HTML that reaches the preview is the safe structure the parser itself generates.
Common mistakes and how to fix them
| Symptom | Usual cause |
|---|---|
| Bullet list not rendering | Missing space after the -, or no blank line before the list. |
| Bold or italic ignored | Unmatched * or _, or a space between the marker and the word. |
| Table not forming | The separator row (| --- | --- |) is missing or has the wrong number of columns. |
| Code block leaking formatting | The closing triple backticks are missing, so the fence never ends. |
When to use it
Reach for a live previewer whenever you are drafting content in Markdown and want confidence before publishing: writing a README, composing release notes, drafting a blog post for a static-site generator, or building an email in a Markdown-aware editor. It is also a quick way to convert a snippet of Markdown into HTML you can paste into a CMS that does not accept Markdown directly — copy the generated markup and drop it in.
Because the whole tool runs in the browser with no libraries and no network calls, it is safe for private drafts and works offline once the page has loaded. Your text is read only to build the preview and is discarded the moment you clear the field or leave the page.