Edwin LabHow to preview Markdown
- Paste your README or documentation draft.
- Select Preview Markdown to parse and sanitize it locally.
- Review the sandboxed preview or copy the sanitized HTML source. Download creates a standalone HTML preview.
Supported syntax includes headings, paragraphs, emphasis, lists, blockquotes, fenced code, tables, strikethrough, and inert task markers.
Links, images, and raw HTML
Raw HTML is displayed as escaped text. Links appear as labels without destinations, and images appear as alt-text placeholders. No URL, image, or resource attributes are kept in the sanitized fragment. Task list checkboxes are rendered as the text [ ] or [x].
This tool uses Marked's GitHub Flavored Markdown option; it does not promise exact GitHub rendering. Line breaks, plugins, front matter, Mermaid, math, and HTML playground behavior are not included.
Limits and privacy
Input is limited to 256 KiB UTF-8, generated HTML to 1 MiB, 20,000 tokens, 100 nested levels, and a 3-second parsing worker deadline. Synchronous browser sanitization has a separate performance cost. Input is not uploaded, saved, or placed in the page URL.
Can I preview raw HTML?
No. Raw HTML is escaped and appears as text.
Why don't links or images load?
Destinations are intentionally omitted so the preview does not navigate or fetch resources.
Does this match GitHub Markdown exactly?
No. This is a bounded preview for common Markdown and GFM syntax.
What is included in the HTML download?
A trusted wrapper with a restrictive Content Security Policy and the sanitized fragment only.