Markdown to HTML
Live preview and convert markdown instantly.
Understanding Markdown and HTML Conversion
Markdown is a lightweight markup language with plain-text-formatting syntax. It is widely adopted by developers and writers to author blogs, documentation, and technical notes, which are subsequently compiled into highly accessible semantic HTML.
The Markup Standard
Created by John Gruber in 2004, Markdown aims to be easy-to-read and easy-to-write in its raw form. It translates directly to HTML tags, enabling developers to write structured formats without typing verbose tags manually.
Parsing & AST Compilation
Our parser uses the high-performance marked package to tokenize plain text input into an Abstract Syntax Tree (AST), ensuring nested lists, code blocks, tables, and strong styling are correctly compiled into standard valid HTML elements.
Sandboxed Preview Security
The live preview renders inside a fully sandboxed iframe with scripts disabled, so even a shared link can never run code on this page. All parsing happens locally in your browser — no tracking scripts, no servers.
Secure, Client-Side Conversions
ZeroServer.tools is built on the philosophy of full developer privacy. All compilation runs inside your browser, and the rendered preview is isolated in a script-disabled sandbox — the converted HTML stays 100% private and can never execute injected code.
Built and maintained by Meet Shah · Last updated
What this tool is used for
- Checking how a README will render before pushing it.
- Producing HTML for a CMS field that does not accept Markdown.
- Working out why a list or a table is not rendering as you intended.
- Converting notes into HTML for an email or a static page.
- Comparing how a construct renders against what you expected the flavour to support.
Frequently Asked Questions
- What Markdown syntax does this converter support?
- CommonMark specification: headings (#), bold (**), italic (*), strikethrough (~~), ordered/unordered lists, fenced code blocks, blockquotes (>), tables, links, and inline images.
- Can I use the HTML output directly on my website?
- Yes, but sanitize it first if Markdown was entered by end users (to prevent XSS). The output is raw HTML — inject it via innerHTML on trusted content, or through a sanitizer for user-generated content.
- What's the difference between Markdown and HTML?
- Markdown is a lightweight markup language designed for human readability — asterisks for bold, # for headings. HTML is the web rendering format. This tool converts Markdown to the HTML your browser renders.
- Does Markdown preserve single line breaks?
- No — a single newline within a paragraph becomes a space. To force a line break, add two trailing spaces or a backslash before the newline. Triple-backtick code blocks preserve all whitespace.
- Can I preview the rendered output?
- Yes — switch to the Preview tab to see the formatted output update in real-time as you type. The HTML Source tab shows the raw HTML for copying into your project.
Common errors and gotchas
- Assuming one Markdown. Tables, footnotes and task lists are extensions, and support varies by renderer.
- Forgetting that a list needs a blank line before it in many parsers, or it joins the paragraph above.
- Using a single line break and expecting a new line. Most flavours need two spaces or a blank line.
- Mixing raw HTML into Markdown and hitting a renderer that escapes it rather than passing it through.
- Indenting a code block by three spaces instead of four, which makes it a paragraph.