Markdown to HTML Converter

Convert Markdown into HTML in the browser. Supports GitHub Flavored Markdown including tables and task lists.

Private browser-side processing
Input MarkdownMarkdown
Supports headings, lists, tables, code blocks, and other GFM syntax.
13 lines · 199 bytes
Output HTMLHTML
No action has been run yet.
0 lines · 0 bytes

How FormatArc converts Markdown to HTML

Conversion details

FormatArc uses marked with gfm: true and breaks: false. # to ###### become <h1> to <h6>, **bold** becomes <strong>, _italic_ becomes <em>, fenced code blocks (```) become <pre><code>, and pipe tables become <table>. GFM extensions are enabled, so task lists ( - [x] item ) render as checkboxes and strikethrough (~~text~~) becomes <del>. With breaks: false, a single newline is treated as a paragraph break instead of a <br> (CommonMark behavior).

Limitations

Math notation (KaTeX, MathJax) and diagram syntax (Mermaid, PlantUML) are not converted. YAML or TOML frontmatter is treated as plain text — neither stripped nor parsed. The output HTML is not sanitized; if you render user-supplied Markdown on the web, run the result through DOMPurify or a similar library first. Conversion is synchronous, so multi-megabyte input may briefly block the UI.

Privacy & local processing

All Markdown is converted in your browser by static JavaScript. The Markdown content is not uploaded to any server, and no signup or API key is required. FormatArc is built with Next.js static export, so this page ships only static HTML and client-side code.

Also available as CLI and Chrome extension

Need the same conversion in a build pipeline or terminal? FormatArc ships as a CLI on npm (npx formatarc md-to-html input.md). For browser-based formatting without leaving the active tab, FormatArc also has a Chrome extension that formats JSON and YAML in place. See the related articles below for details.

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Related articles

CommonMark vs GFM: Are Tables Part of the Core Spec?CommonMark's core spec does not define table syntax. GFM adds tables, task lists, strikethrough, and extended autolinks as extensions. Compare the 5 differences and see which platforms (GitHub, GitLab, Obsidian, Hugo, Astro) follow which dialect — convert in-browser, no sign-up.Markdown to HTML for Developers — Browser, Pandoc, marked.jsCompare browser conversion, Pandoc, marked.js, and markdown-it. See examples for GFM tables, fenced code, task lists, and clean HTML output.