In this article
What Is Markdown?
Markdown is a lightweight markup language created by John Gruber in 2004. It uses simple punctuation-based syntax to add formatting to plain text — headings with #, bold with **, links with [text](url) — which renders to formatted HTML. Its simplicity made it the universal standard for developer documentation.
Markdown is used everywhere: GitHub README files, Stack Overflow answers, Slack messages, Notion pages, documentation sites, and blog platforms. Most developers write Markdown daily without thinking about it.
How Markdown Preview Works
CheckTown's Markdown preview renders your Markdown to HTML in real time as you type.
- CommonMark compliance — renders standard Markdown according to the CommonMark specification
- GFM extensions — supports GitHub Flavored Markdown including tables, task lists, and strikethrough
- Syntax highlighting — code blocks are highlighted for common programming languages
Try it free — no signup required
Preview Markdown →When To Use Markdown Preview
Markdown preview is useful for any writing workflow where you need to verify rendering before publishing.
- README files — draft and preview README.md files before pushing to GitHub
- Documentation — write and preview technical documentation before publishing to docs sites
- Blog posts — compose blog posts in Markdown and preview the formatted output
Frequently Asked Questions
What is the difference between Markdown flavors?
The original Markdown spec left many edge cases undefined, leading to multiple incompatible implementations. CommonMark is a standardized specification that resolves ambiguities. GitHub Flavored Markdown (GFM) extends CommonMark with tables, task lists, and autolinks. Most platforms use either CommonMark or GFM.
Can Markdown include raw HTML?
Yes, most Markdown processors allow raw HTML tags to be embedded directly in Markdown documents. This is useful for advanced formatting not supported by Markdown syntax. However, many platforms sanitize HTML for security, so raw HTML may be stripped in user-generated content contexts.
How do I add a table in Markdown?
Tables use pipe characters and hyphens: | Header 1 | Header 2 | on the first row, | --- | --- | on the second row for the separator, then data rows. Column alignment is controlled by the colon position in the separator: :--- for left, :---: for center, ---: for right.