What is Markdown Previewer?
Markdown is the lightweight formatting syntax behind READMEs, blog posts, chat messages, documentation, and countless other places where you want simple, readable formatting without writing raw HTML. Because Markdown is plain text, it's easy to write anywhere — but it's also easy to get the syntax slightly wrong and not notice until you've already published it.
This previewer renders your Markdown as you type, side by side with the source, so you can catch formatting mistakes immediately — a missing space after a #, an unclosed code fence, or a list that didn't separate from the paragraph above it — before you commit a README, publish a post, or send a formatted message.
When to Use This Calculator
- Writing a GitHub or GitLab README and want to verify formatting before committing
- Drafting a Markdown post for a blog platform, documentation site, or wiki
- Checking a Markdown email or chat message renders correctly before sending
- Learning Markdown syntax by experimenting with different formatting and seeing instant results
- Converting a short Markdown snippet to HTML for pasting into a CMS or email template
- Debugging a Markdown document where some formatting isn't rendering as expected
Steps:
- Type or paste your Markdown into the left panel.
- Watch the rendered HTML preview update instantly on the right.
- Adjust your syntax until the preview matches what you intended.
- Copy your finished Markdown source once you're happy with the result.
Formula
# Heading →
Heading
**bold** → bold *italic* → italic `code` →code
[text](url) → text
- item → - item
Use Cases
- Previewing a GitHub or GitLab README before committing it
- Drafting formatted messages for Slack, Discord, or other Markdown-supporting chat apps
- Checking blog post or documentation formatting before publishing
- Learning Markdown syntax by experimenting and seeing immediate results
- Quickly converting a short Markdown snippet to HTML for pasting elsewhere
Key Benefits
- See your Markdown rendered instantly, side by side with the source
- Catch syntax mistakes before publishing anywhere
- Runs entirely offline in your browser — nothing is uploaded
- Free, no sign-up, no file size limits for typical use
Pro Tips
- Add a blank line before and after lists and code blocks for the most reliable rendering across different Markdown parsers
- Use double asterisks for bold and single asterisks (or underscores) for italics to avoid ambiguity
- Preview in this tool first, then check the target platform (GitHub, Slack, etc.) since some support extra syntax like tables
- Keep headings sequential (don't skip from # to ###) for better document structure and accessibility
Common Mistakes to Avoid
- Forgetting the blank line needed between a paragraph and a following list
- Missing the space after # symbols in headings, which prevents them from rendering
- Leaving a code fence (```) unclosed, which swallows the rest of the document as code
- Using single asterisks for bold instead of double asterisks, producing italics instead
Key Terms Explained
- CommonMark: A standardized specification of Markdown syntax, designed to reduce inconsistencies
- GFM: GitHub-Flavored Markdown, an extended dialect supporting tables and task lists
- Code fence: A block delimited by triple backticks (```) used to format multi-line code
- Inline formatting: Formatting applied within a single line, like *italic* or `code`, as opposed to block-level elements
Related Concepts
Example
Typing "## Hello\n\nThis is **bold** and this is *italic*." renders as a level-2 heading followed by a paragraph with bold and italic text.
Interpreting Your Results
The left panel shows your raw Markdown source text, and the right panel renders it as formatted HTML in real time. Every keystroke updates the preview instantly, so you can see the effect of each syntax element immediately.
Common rendering issues usually come down to spacing. A blank line is required between a paragraph and a following list for most renderers. Headings need a space after the # symbols. Code fences (```) need to be on their own line to trigger code block rendering.
The preview is a close approximation of how your Markdown will appear on most platforms (GitHub, Slack, Discord, etc.), but each platform has its own renderer with slight variations. Always do a final check on the target platform for anything beyond basic formatting.