What is Markdown?
Markdown is a lightweight markup language created by John Gruber in 2004, designed to be readable as plain text while being convertible to HTML. The syntax was inspired by plain text email conventions — using asterisks for emphasis (*bold*), hyphens for lists, and underscores for italics. Today Markdown is the standard format for README files, documentation, blog posts, forum comments (GitHub, Reddit), and note-taking apps (Notion, Obsidian).
The split-pane editor
The previewer uses a split-pane layout: Markdown source on the left, rendered HTML preview on the right, updating in real time as you type. Switch to Editor-only mode to focus on writing, or Preview-only mode to read the rendered output full-width. The word count and character count update live in the status bar at the bottom.
GitHub Flavored Markdown (GFM)
GitHub Flavored Markdown extends the original Markdown specification with practical additions: fenced code blocks with syntax highlighting (```javascript), task lists (- [x] Done, - [ ] Todo), tables with pipe syntax, strikethrough text (~~crossed out~~), and auto-linking of URLs. The previewer supports all GFM features, making it suitable for previewing README files exactly as they will appear on GitHub.
Code blocks and syntax
Fenced code blocks use triple backticks with an optional language identifier: ```python. The previewer renders code blocks in a monospace font with a distinct background. For inline code (variable names, commands, file paths), use single backticks: `npm install`. Code blocks preserve whitespace and line breaks exactly as typed.
Tables
Markdown tables use pipes (|) to separate columns and hyphens for the header separator row. Alignment can be specified with colons: |---| (left), |:---:| (centre), |---:| (right). Tables are one of the less intuitive parts of Markdown syntax — seeing them render in real time in the previewer makes it much easier to build them correctly.
Exporting to HTML
The "Copy HTML" button copies the fully rendered HTML to your clipboard. This HTML can be pasted directly into any system that accepts HTML — a CMS, an email template, a static HTML file. The HTML is clean and semantic, using standard tags (h1–h6, p, ul, ol, pre, code, table) without extra classes or wrapper divs.