Online Markdown Editor

Write Markdown on the left and see the live HTML preview on the right. Supports GitHub Flavored Markdown.

Markdown

Preview

What is a Markdown Editor?

A Markdown editor is a text editor designed specifically for writing Markdown, a lightweight markup language that uses plain-text formatting syntax. Unlike word processors that use a "What You See Is What You Get" (WYSIWYG) approach, a Markdown editor lets you write in plain text using simple symbols like # for headings, ** for bold, and - for lists. The editor then renders this plain text into styled HTML.

An online Markdown editor with live preview is the most common type. It splits the screen into two panes: a plain text editor on the left and a rendered HTML preview on the right. As you type, the preview updates instantly, allowing you to see exactly how your document will look without having to compile it manually. This immediate feedback loop is invaluable for learning Markdown syntax, debugging formatting issues, and writing documentation, README files, blog posts, and notes.

Why Use Markdown?

Markdown has become the de facto standard for writing technical documentation, README files on GitHub, and notes in tools like Obsidian and Notion. Here is why it is so widely adopted:

Plain Text is Future-Proof: Markdown files are just text files (.md). They can be opened on any device, in any text editor, without proprietary software. Your content will never be locked behind a specific application.
Human-Readable Syntax: Even without rendering, Markdown is easy to read. A heading is just a # followed by text. A list is just a hyphen. This makes it easy to review and edit documents directly in their raw form.
Version Control Friendly: Because Markdown is plain text, it works flawlessly with Git. You can track changes line-by-line, collaborate with others via pull requests, and resolve conflicts just like you would with code.
Platform Independent: Markdown is supported by virtually every modern platform: GitHub, Reddit, Stack Overflow, Discord, WordPress, and countless others. Learning it once means you can use it everywhere.

How a Live Preview Markdown Editor Works

A Markdown editor with live preview works by constantly parsing your input text and updating the preview pane. The process involves three steps:

Parsing: The editor takes your raw Markdown string and passes it through a parser. This tool uses marked.js, a fast and widely used Markdown parser that supports GitHub Flavored Markdown (GFM). GFM adds features like tables, task lists, and strikethrough text on top of the standard Markdown specification.
Rendering: The parser converts the Markdown syntax into HTML tags. For example, # Hello becomes <h1>Hello</h1>.
Sanitization: Because Markdown allows raw HTML to be embedded, there is a security risk. If you paste malicious HTML into the editor, it could execute scripts when rendered. To prevent this, the tool uses DOMPurify to sanitize the generated HTML, stripping out any potentially dangerous tags or attributes while preserving safe, standard formatting.

This entire process happens in your browser, on every keystroke. Modern JavaScript engines are fast enough to render even large documents without noticeable lag.

GitHub Flavored Markdown (GFM) vs. Standard Markdown

The original Markdown specification, created by John Gruber in 2004, was relatively minimal. Over time, platforms like GitHub added their own extensions. GitHub Flavored Markdown (GFM) has become the most popular standard because it is used across GitHub, Stack Overflow, and many modern editors. This tool supports GFM, which means you get:

Tables: Create tables using pipes | and hyphens -.
Task Lists: Create interactive checklists using - [ ] for incomplete and - [x] for complete tasks.
Strikethrough: Wrap text in double tildes ~~text~~.
Fenced Code Blocks: Use triple backticks ``` to denote code blocks, with optional language tags for syntax highlighting.

Common Markdown Mistakes and How to Fix Them

Even experienced Markdown users make mistakes. Here are the most common ones:

Missing Blank Lines: In Markdown, a blank line is required to separate paragraphs or to start a list after a paragraph. If you forget the blank line, the parser may merge the elements or fail to render the list correctly.
Underscores in Words: Using underscores (_) for italics inside a word (e.g., some_variable_name) can cause the parser to misinterpret the text. Use asterisks (*) instead, or escape the underscores with a backslash.
Indentation for Nested Lists: Nested lists require specific indentation (usually 2 or 4 spaces) to be recognized as children of the parent list. Incorrect indentation will flatten the list.
Forgetting the Space After a Hash: A heading requires a space after the hash: # Heading works, but #Heading does not.

How to Use This Tool

Write or Paste Markdown: Use the left pane to write your Markdown. You can use the toolbar buttons to insert common syntax without memorizing the symbols.
View Live Preview: The right pane updates instantly. Scroll through the preview to verify that your formatting is correct.
Copy or Download: Use the buttons below the editor to copy the raw Markdown, copy the generated HTML (for pasting into a website), or download the Markdown as a .md file.
Clear: The "Clear" button resets both panes.

Frequently Asked Questions

Is my Markdown sent to a server?

No. The editor, parser, and preview all run entirely in your browser using client-side JavaScript. Your text never leaves your device and is not stored or logged anywhere. This makes it safe for confidential notes and proprietary documentation.

Does this editor support tables?

Yes. It supports GitHub Flavored Markdown (GFM), which includes table syntax. You can create tables using pipes | and hyphens.

Can I use this editor to write README files for GitHub?

Yes. This editor supports the same GitHub Flavored Markdown syntax used by GitHub. You can write your README, preview it, and download the .md file to commit to your repository.

Does the preview support code syntax highlighting?

The preview correctly formats code blocks with a monospace font and background color. Full syntax highlighting (colored keywords) requires a separate highlighting library, which is not included in this lightweight tool.

Why does my HTML not render?

This tool sanitizes the output using DOMPurify to prevent XSS attacks. If you embed raw HTML tags like <script> or <iframe>, they will be stripped for security reasons. Standard Markdown formatting and safe HTML tags (like <b> or <i>) are preserved.

What is the difference between Markdown and HTML?

Markdown is a lightweight markup language designed for readability. HTML is a complex markup language designed for web browsers. Markdown is much easier to write and read, and it compiles down to HTML.

Can I use this editor offline?

After the page loads, the editor works offline because all parsing and rendering happen in your browser. You can disconnect from the internet and continue writing.

How do I create a nested list?

Indent the child list items by 2 or 4 spaces relative to the parent item. For example: - Item 1\n - Sub-item.

Why is my heading not rendering?

Ensure you have a space after the hash symbol. # Heading works, but #Heading does not.

Does this tool support LaTeX math formulas?

No. LaTeX math support requires a dedicated math rendering library (like KaTeX or MathJax), which is not included in this lightweight editor.

Can I export the document as PDF?

This tool does not have a direct PDF export button. However, you can copy the generated HTML into a word processor or use your browser's "Print" function on the preview pane to save it as a PDF.

How do I create a checkbox or task list?

Use the syntax - [ ] for an incomplete task and - [x] for a completed task. This is a GitHub Flavored Markdown feature.

What is GitHub Flavored Markdown (GFM)?

GFM is a strict superset of standard Markdown that adds features like tables, task lists, and strikethrough. It is the standard used by GitHub, Stack Overflow, and many modern editors.

Why are underscores in my variable names causing italics?

Markdown interprets paired underscores as italic formatting. To display literal underscores, escape them with a backslash: some\_variable\_name.

Does the editor support drag-and-drop images?

No. This tool is a text-based editor. To include images, you must use the Markdown image syntax ![Alt](url) and provide a URL to an image hosted elsewhere.

What is the maximum document size?

The limit depends on your browser's memory. Most modern browsers can handle Markdown documents of several megabytes without issue. For very large files, performance may degrade slightly.

Can I copy the generated HTML to my website?

Yes. Use the "Copy HTML" button. This copies the sanitized HTML to your clipboard, ready to be pasted into a blog post, CMS, or static site.

How do I create a blockquote?

Start a line with a greater-than symbol followed by a space: > Your quote here.

Does this tool support footnotes?

Standard GitHub Flavored Markdown does not support footnotes. Some extended Markdown flavors do, but this tool follows the GFM specification.

Why is my list not rendering correctly after a paragraph?

You must include a blank line between a paragraph and the start of a list. Without a blank line, the parser treats the list items as part of the paragraph.

Is this tool free to use?

Yes. It is completely free, requires no sign-up, and has no usage limits. All processing is local, so there are no server costs.

Can I use this editor on my phone?

Yes. The interface is fully responsive and stacks the editor and preview panes vertically on mobile devices.