Online Markdown Viewer

Free Online Markdown Preview & Viewer

Preview and view Markdown online — drop any .md, .mmd, or .mermaid file to render it instantly in your browser. No sign-up, no upload, no server. Everything runs locally in your browser.

• GitHub Flavored Markdown — tables, task lists, fenced code blocks, strikethrough
• Mermaid diagrams — flowcharts, sequence, Gantt, ER, class diagrams and more
• Standalone .mmd / .mermaid files — open Mermaid diagram files directly
• Table of Contents — auto-generated from headings with scroll sync
• Dark mode — follows your system preference automatically
• Privacy-first — files are read locally, never leave your device

How It Works

1. Drop or choose a file — drag any .md file onto the page, or click "Choose File" to browse
2. Instant preview — your Markdown renders immediately with full formatting, syntax highlighting, and Mermaid diagrams
3. Navigate with Table of Contents — headings generate a clickable sidebar that scrolls with you

Your files stay on your device. Nothing is uploaded to any server — the entire viewer runs in your browser using JavaScript.

Who Uses This Viewer

• Developers — preview README files, documentation, and specs before committing
• Teams reviewing AI output — render Markdown from ChatGPT, Claude, Cursor, and other AI tools
• Non-technical users — view .md files received from developers without installing any software
• Technical writers — check Markdown formatting and Mermaid diagrams in a clean environment

FAQ

Is this markdown viewer really free?

Yes. The online viewer is completely free with no limits, no account required, and no ads. For advanced features like inline editing, Git history, and multi-file tabs, see MDViewer for macOS.

Are my files uploaded to a server?

No. Your files never leave your browser. The viewer reads files locally using the browser's File API. There is no server-side processing — everything runs in JavaScript on your device.

What file formats are supported?

The viewer supports .md and .markdown files (GitHub Flavored Markdown), plus standalone .mmd and .mermaid diagram files.

Can I preview Mermaid diagrams?

Yes. Mermaid code blocks inside Markdown files render as interactive SVG diagrams — flowcharts, sequence diagrams, Gantt charts, ER diagrams, class diagrams, and more. You can also open standalone .mmd files directly.

Want to edit Markdown, track git history, and search across files? Download MDViewer for macOS →