Markdown Editor

Online Markdown Editor — Write and Preview Markdown with Live HTML Output

Markdown does something deceptively simple: it turns plain text into formatted content using a handful of punctuation conventions. A hash before a line makes it a heading. Two asterisks around a word make it bold. A hyphen at the start of a line makes it a list item. The result is a format that reads naturally as raw text in any editor but converts mechanically to clean HTML. Written by John Gruber and Aaron Swartz in 2004, Markdown was designed with exactly that dual nature in mind — human-readable in source form, machine-convertible to presentable output. Twenty years later, it has become the dominant format for technical writing, documentation, and content that lives alongside code.

This editor gives you a live split-pane interface: write on the left, see formatted output on the right. It supports GitHub-Flavored Markdown (GFM) — the extended specification that adds tables, task lists, strikethrough, fenced code blocks with syntax highlighting, and autolinked URLs. Your draft auto-saves to browser localStorage. Nothing is ever sent to any server.

Core Markdown Syntax

Headings: Hash symbols create heading levels: # H1 through ###### H6. The number of hashes determines the level. H1 is typically the page title; H2 through H4 are section and sub-section headings. Most Markdown parsers also support setext-style headings using underlines (= for H1, - for H2), though ATX-style (hashes) is more common in practice.

Text formatting: Bold wraps text in double asterisks: **bold**. Italic uses single: *italic*. Strikethrough (GFM) uses double tildes: ~~deleted~~. Bold italic combines both: ***bold italic***. Inline code uses single backticks: `variable`.

Links and images: Inline links use [text](URL). Reference-style links separate the URL for cleaner source: [text][ref] with [ref]: URL elsewhere. Images add an exclamation prefix: ![alt text](image-url).

Lists: Unordered lists use -, *, or + at the line start. Ordered lists use 1., 2., etc. Nested lists are created by indentation. GFM task lists use - [ ] (unchecked) and - [x] (checked).

Code blocks: Fenced code blocks use triple backticks with an optional language identifier for syntax highlighting: ```javascript. The language tells the renderer which highlighting rules to apply.

Blockquotes: Lines starting with > become blockquotes, rendered with a left border and indented style. Tables (GFM): Pipe characters separate columns, hyphens define the header separator row, and colons in the separator control alignment: |:---| left, |:---:| center, |---:| right. Horizontal rules: Three or more hyphens, asterisks, or underscores on their own line.

Where Markdown Is Used in Practice

GitHub, GitLab, Bitbucket: README files, wiki pages, issue descriptions, pull request comments — all support Markdown. Writing clearly formatted issues and PR descriptions with code blocks, lists, and headings is a professional expectation in most development contexts.

Documentation platforms: MkDocs, Docusaurus, ReadTheDocs, and VitePress build entire documentation sites from Markdown files. Teams write docs in plain text alongside code, in the same repository, with the same version control workflow.

Static site generators: Jekyll, Hugo, Eleventy, Gatsby, and Astro use Markdown as their primary content format. Blog posts and pages are written as .md files and converted to HTML at build time, keeping content separate from presentation.

Note-taking: Obsidian, Notion, Bear, Typora, and many other tools store notes as Markdown. Notes written in Markdown are portable — open the .md file in any text editor and they are fully readable without any application.

Standard Markdown vs. GitHub-Flavored Markdown

Gruber's original 2004 spec defined the core syntax — headings, lists, code, links, images, blockquotes, and text formatting. It was deliberately minimal, but left many edge cases underspecified, leading to inconsistent behavior across parsers.

GitHub-Flavored Markdown (GFM), specified in 2017 based on the CommonMark standard, resolved many ambiguities and added features: fenced code blocks, tables, task lists, strikethrough, autolinked URLs, and disallowed raw HTML for security. GFM has effectively become the dominant dialect — most modern Markdown tools support it or a close variant. This editor uses GFM-compatible parsing, so your output will render consistently with what GitHub and most platforms display.

Frequently Asked Questions About Markdown