Markdown Previewer
Write Markdown and preview rendered HTML with syntax highlighting and copy support.
About Markdown Previewer
Markdown is a lightweight markup language created by John Gruber in 2004 with the goal of being as readable as possible in its raw text form while still converting cleanly to structurally valid HTML. Unlike HTML, which wraps content in verbose opening and closing tags, Markdown uses minimal punctuation characters -- hash signs for headings, asterisks for emphasis, hyphens for lists, and backticks for code -- that visually suggest the formatting they produce. This design philosophy means a Markdown document is nearly as easy to read in a plain text editor as it is in its rendered form, making it the preferred writing format for developers, technical writers, and anyone who values both human readability and structured output.
GitHub Flavored Markdown (GFM) extended the original Markdown specification with features essential for software development workflows. GFM introduced fenced code blocks with syntax highlighting (using triple backticks with a language identifier), tables with pipe-delimited columns, task lists with checkbox syntax, strikethrough text, and automatic URL linking. These additions made Markdown suitable not just for simple documents but for comprehensive technical documentation, issue tracking, pull request descriptions, and project wikis. The CommonMark specification later formalized Markdown's parsing rules to eliminate ambiguities in the original description, and GFM builds on CommonMark as its foundation.
Markdown has become the de facto standard for developer documentation across the software industry. README files, API documentation, changelogs, contributing guides, architecture decision records, and static site content are overwhelmingly written in Markdown. Platforms including GitHub, GitLab, Bitbucket, Stack Overflow, Reddit, Discord, Slack, Notion, and Obsidian all support Markdown rendering. Static site generators like Jekyll, Hugo, Gatsby, Next.js, and Astro use Markdown files as their primary content source. The format's simplicity, portability, and version-control friendliness -- since Markdown files are plain text, they produce clean diffs in Git -- explain why it has displaced richer but heavier formats for most developer-facing writing.
How to Use the Markdown Previewer
- Type or paste your Markdown content into the editor panel on the left side of the tool.
- Watch the rendered HTML preview update in real-time on the right panel as you write, giving you immediate visual feedback.
- Use standard Markdown syntax: # for headings (## for h2, ### for h3), **bold**, *italic*, - or * for unordered lists, 1. for ordered lists.
- Add code blocks by wrapping inline code in single backticks or creating fenced blocks with triple backticks, optionally specifying a language for syntax highlighting.
- Include links with [text](url) syntax and images with  syntax to verify they render correctly.
- Switch to the HTML source view to inspect the generated HTML markup, which you can copy for use in web pages, emails, or CMS fields.
- Copy the rendered HTML using the copy button to transfer the markup to your target application or document.
Common Use Cases
Writing and Previewing README Files
A project README is often the first thing developers and users see when visiting a repository. Previewing the README before committing ensures that headings are properly nested, badges render correctly, links point to the right destinations, code examples are properly fenced and highlighted, and the overall document structure is clear and professional. This is especially valuable when the README includes complex elements like tables, nested lists, or embedded images that are difficult to verify in raw text form.
Drafting Technical Documentation
API references, architecture guides, onboarding documents, and runbooks are commonly authored in Markdown for compatibility with documentation platforms like MkDocs, Docusaurus, and GitBook. Previewing documentation during writing catches formatting issues such as broken link syntax, improperly indented nested lists, missing blank lines before code blocks, and table alignment problems before the content is published or committed to the documentation repository.
Composing GitHub Issues and Pull Request Descriptions
Well-formatted GitHub issues and PR descriptions use Markdown features including task lists for tracking sub-tasks, fenced code blocks for reproducing bugs or showing proposed changes, tables for comparing options, and headings for organizing long descriptions. Previewing the Markdown before submitting ensures the formatting renders as intended and that code snippets, which often contain characters with special Markdown meaning, display correctly rather than being interpreted as formatting.
Generating HTML Content from Markdown Source
Content authors who prefer writing in Markdown but need HTML output for websites, newsletters, or CMS platforms can use the previewer to write content and then copy the generated HTML. This workflow combines the writing speed and readability of Markdown with the universal compatibility of HTML, avoiding the need to hand-write HTML tags while still producing clean, semantic markup suitable for any web context.
Frequently Asked Questions
What is the difference between standard Markdown and GitHub Flavored Markdown (GFM)?
Standard Markdown, as defined by John Gruber's original specification and later formalized by CommonMark, supports headings, emphasis, links, images, blockquotes, code spans, code blocks (indented by 4 spaces), horizontal rules, and lists. GFM extends this with fenced code blocks using triple backticks (with optional language identifiers for syntax highlighting), pipe-delimited tables, task lists with [ ] and [x] checkbox syntax, strikethrough text using ~~double tildes~~, automatic URL linking (bare URLs become clickable without angle brackets), and disallowed raw HTML tags for security. Most modern Markdown renderers support GFM by default.
Why does my Markdown list or code block not render correctly?
The most common cause is missing blank lines. In Markdown, a blank line is required before and after code blocks, between a paragraph and a list, and between a heading and the content that follows it. Without these blank lines, the parser may treat the content as a continuation of the preceding paragraph rather than a new block element. For nested lists, consistent indentation is critical -- each nesting level typically requires 2 or 4 spaces (depending on the parser). Mixing tabs and spaces for indentation can also produce unexpected results since parsers may interpret them differently.
How do I include literal asterisks, backticks, or other Markdown characters in my text?
Prefix the character with a backslash to escape it: \* produces a literal asterisk, \` produces a literal backtick, \# produces a literal hash sign, and so on. For backticks within inline code, use double backticks as the delimiter (`` `code with ` backtick` `` becomes `code with ` backtick`). For content that contains many special characters, a fenced code block (triple backticks) will treat everything inside as literal text without any Markdown interpretation, which is the simplest approach for code snippets.
Can Markdown include raw HTML tags?
Yes, the Markdown specification allows inline HTML. You can embed HTML tags directly in a Markdown document and most parsers will pass them through to the rendered output. This is useful for features Markdown does not natively support, such as custom div containers with CSS classes, definition lists (in parsers that do not support them natively), details/summary collapsible sections, or complex table layouts with colspan and rowspan. However, Markdown syntax is not processed inside HTML block-level elements, so you cannot mix Markdown formatting inside a <div> tag. Many platforms also sanitize HTML in Markdown for security, stripping script tags and event handlers.
What is the best way to create tables in Markdown?
GFM tables use pipes (|) to separate columns and hyphens (-) to create the header separator row. A basic table looks like: | Header 1 | Header 2 | followed by | --- | --- | and then data rows. Column alignment is controlled by colons in the separator row: :--- for left-aligned, :---: for centered, and ---: for right-aligned. The pipes do not need to be vertically aligned in the source text, though aligning them improves readability. For complex tables with merged cells or multi-line content, you may need to fall back to raw HTML table tags within your Markdown document.
Is Markdown suitable for long-form documents like books or specifications?
Markdown works well for moderately complex documents but has limitations for very long or highly structured content. It lacks native support for footnotes (though some extensions add them), cross-references between sections, figure numbering, table of contents generation, and advanced layout control. For book-length content, extended Markdown processors like Pandoc add these features and can output to PDF, EPUB, and DOCX formats. For specifications and standards documents, formats like AsciiDoc or reStructuredText offer richer semantic markup. That said, many successful books and comprehensive documentation sites have been written entirely in Markdown using static site generators that supplement the format with plugins and frontmatter metadata.