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<!DOCTYPE html>
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<title>Markdown Editor & Live Preview — GFM | FreeDevTool</title>
<meta name="description" content="Free Markdown editor with live preview — GFM tables, code blocks, task lists, strikethrough. Convert MD to HTML. Browser-only.">
<meta name="robots" content="index, follow">
<meta name="author" content="Anees Ur Rehman">
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<meta property="og:title" content="Markdown Editor & Preview Online — Free">
<meta property="og:description" content="Live markdown editor with split-screen preview. Convert to HTML. GitHub Flavored Markdown supported.">
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<h1>Markdown Editor & Live Preview Online</h1>
<p class="tool-description">
Write markdown and see a live rendered preview side by side. This free markdown editor supports <a href="https://github.github.com/gfm/" rel="noopener" style="color:var(--accent)">GitHub Flavored Markdown (GFM)</a>: tables, fenced code blocks with language syntax highlighting, task lists, strikethrough, autolinks. Convert markdown to clean, semantic HTML with one click. Perfect for writing README files, documentation, blog posts, and PR descriptions. All rendering happens in your browser — nothing is uploaded.
</p>
<div class="last-updated">Last updated: May 2026 · Written by <a href="/about">Anees Ur Rehman</a>, full-stack developer</div>
</div>
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<div class="dot dot-red"></div><div class="dot dot-yellow"></div><div class="dot dot-green"></div>
<span class="tool-card-title">markdown-preview.tool</span>
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<div class="editor-split">
<div class="editor-pane">
<div class="pane-header"><span>Markdown</span><span id="md-count">0 words</span></div>
<textarea class="editor-textarea" id="md-input" oninput="renderMd()" placeholder="# Hello World
Write your **markdown** here...
- Item 1
- Item 2
```js
console.log('Hello!');
```
">
# Welcome to FreeDevTool Markdown Editor
Write **bold**, *italic*, and ~~strikethrough~~ text easily.
## Features
- Live preview as you type
- GitHub Flavored Markdown
- Code blocks with syntax hints
- Tables, task lists, blockquotes
## Code Example
```javascript
function greet(name) {
return `Hello, ${name}!`;
}
```
## Table Example
| Feature | Supported |
| --- | --- |
| Bold / Italic | ✓ |
| Code Blocks | ✓ |
| Tables | ✓ |
| Task Lists | ✓ |
> "Markdown is intended to be as easy-to-read and easy-to-write as is feasible." — John Gruber
---
Made with ♥ by [FreeDevTool](https://freedevtool.org)
</textarea>
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<div class="pane-header"><span>Preview</span><button class="btn btn-ghost" style="padding:3px 8px;font-size:10px" onclick="copyHtml()">Copy HTML</button></div>
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<button class="btn btn-ghost" onclick="copyHtml()">Copy</button>
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<!-- =============================================================
LONG-FORM ARTICLE — comprehensive guide for E-E-A-T + ranking.
============================================================= -->
<article>
<p class="aeo-lead" style="font-size:16px;line-height:1.7;color:var(--text);max-width:760px;margin:24px auto 18px;padding:0 4px">
<strong>Markdown</strong> is a lightweight plain-text formatting syntax that converts to HTML — the lingua franca of READMEs, technical docs, and Dev.to articles. GitHub-flavored Markdown (GFM) adds tables, task lists, strikethrough, and fenced code blocks. This <strong>free Markdown preview</strong> renders GFM exactly as GitHub does — no surprises when you push your README.
</p>
<section id="examples" style="max-width:760px;margin:24px auto 32px">
<h2 style="font-size:18px;margin-bottom:14px">Examples</h2>
<div style="background:var(--bg3);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:12px">
<strong style="display:block;color:var(--accent);font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:1px;margin-bottom:6px">GFM task lists§§- [x] Buy milk§§- [ ] Walk the dog§§Renders as checkboxes that match GitHub exactly. Standard CommonMark does NOT support task lists.</strong>
</div>
<div style="background:var(--bg3);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:12px">
<strong style="display:block;color:var(--accent);font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:1px;margin-bottom:6px">GFM tables§§</strong>
</div>
<div style="background:var(--bg3);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:12px">
<strong style="display:block;color:var(--accent);font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:1px;margin-bottom:6px"> Name </strong>
</div>
<div style="background:var(--bg3);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:12px">
<strong style="display:block;color:var(--accent);font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:1px;margin-bottom:6px"> Score </strong>
</div>
<div style="background:var(--bg3);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:12px">
<strong style="display:block;color:var(--accent);font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:1px;margin-bottom:6px">§§</strong>
</div>
<div style="background:var(--bg3);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:12px">
<strong style="display:block;color:var(--accent);font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:1px;margin-bottom:6px">------</strong>
</div>
<div style="background:var(--bg3);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:12px">
<strong style="display:block;color:var(--accent);font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:1px;margin-bottom:6px">------</strong>
</div>
<div style="background:var(--bg3);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:12px">
<strong style="display:block;color:var(--accent);font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:1px;margin-bottom:6px">§§</strong>
</div>
<div style="background:var(--bg3);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:12px">
<strong style="display:block;color:var(--accent);font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:1px;margin-bottom:6px"> Alice </strong>
</div>
<div style="background:var(--bg3);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:12px">
<strong style="display:block;color:var(--accent);font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:1px;margin-bottom:6px"> 95 </strong>
</div>
<div style="background:var(--bg3);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:12px">
<strong style="display:block;color:var(--accent);font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:1px;margin-bottom:6px">§§Pipe-separated tables with optional alignment colons (:--, :--:, --:). Always preview in actual GitHub before publishing.</strong>
</div>
<div style="background:var(--bg3);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:12px">
<strong style="display:block;color:var(--accent);font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:1px;margin-bottom:6px">Fenced code block with language§§Triple backticks plus language hint gets syntax highlighting on GitHub: javascript, python, sql, html, etc. The highlighting engine is Linguist.</strong>
</div>
</section>
<aside class="founder-note" style="max-width:760px;margin:24px auto 32px;padding:20px 24px;background:rgba(0,208,132,0.05);border-left:3px solid var(--accent);border-radius:6px;font-size:14px;line-height:1.7;color:var(--text2)"><div style="font-family:var(--mono);font-size:11px;color:var(--accent);letter-spacing:1.5px;text-transform:uppercase;margin-bottom:10px;font-weight:600">💡 Why I built this</div><p style="margin:0 0 12px">I built this after pushing a README to GitHub and watching the bullet points render as flat text — because my local markdown preview accepted bullets without trailing spaces, but GitHub’s stricter parser required them. This preview matches GitHub-flavored Markdown exactly: same task list rendering, same table parsing, same fenced code block behavior. What you see here is what GitHub will show — no surprises.</p><p style="margin:0;font-size:13px;color:var(--text3)">— <a href="/about" style="color:var(--accent);text-decoration:none">Anees Ur Rehman</a>, full-stack developer</p></aside>
<section class="article-section">
<h2>What is Markdown and why has it conquered the developer world?</h2>
<p><strong>Markdown</strong> is a lightweight markup language created by John Gruber and Aaron Swartz in 2004. The design goal was deceptively simple: a plain-text format that reads naturally as-is, and converts cleanly to HTML when needed. Two decades later, Markdown is the universal write-once-render-everywhere format for technical content — README files on every GitHub repo, posts on Reddit and Stack Overflow, documentation on Notion and Obsidian, blog posts on Substack, slides in Marp, papers in Pandoc, even chat messages in Slack and Discord.</p>
<p>Why did Markdown win where heavier alternatives (HTML, AsciiDoc, RST, BBCode) didn't?</p>
<ul>
<li><strong>Readable in raw form.</strong> A markdown file is meaningful as plain text — you don't need to mentally render it.</li>
<li><strong>Tiny syntax surface.</strong> Headings (<code>#</code>), bold (<code>**</code>), italic (<code>*</code>), links (<code>[text](url)</code>), lists (<code>-</code>), code blocks (<code>```</code>) — that's 90% of what you'll ever use. Five minutes to learn.</li>
<li><strong>Plays well with version control.</strong> Plain-text diffs are clean. Code review on Markdown is sane in a way that Word docs or Notion exports aren't.</li>
<li><strong>Render targets are everywhere.</strong> Every static site generator (Hugo, Jekyll, Eleventy, Astro, Next.js MDX), every developer platform (GitHub, GitLab, Bitbucket, Codeberg), every documentation system (Docusaurus, MkDocs, GitBook, ReadTheDocs).</li>
</ul>
<p>The trade-off: <strong>fragmentation.</strong> The original 2004 spec was incomplete and ambiguous. Different parsers produced different output for the same input. CommonMark (2014) standardized 80% of the syntax; GitHub Flavored Markdown extends it with practical features. This editor renders <strong>GFM</strong>, the dominant variant in 2026.</p>
</section>
<section class="article-section">
<h2>The Markdown family — CommonMark vs GFM vs MultiMarkdown</h2>
<p>"Markdown" today is an umbrella term. Knowing which dialect your platform uses prevents formatting surprises.</p>
<table class="ref-table">
<thead><tr><th>Variant</th><th>Year</th><th>What it adds</th><th>Used by</th></tr></thead>
<tbody>
<tr>
<td><strong>Original Markdown</strong></td>
<td>2004</td>
<td>Headings, emphasis, lists, links, code blocks, blockquotes</td>
<td>Historical artifact — most parsers extend it</td>
</tr>
<tr>
<td><strong>CommonMark</strong></td>
<td>2014</td>
<td>Strict, unambiguous spec. Edge cases formally defined.</td>
<td>Reddit, Discourse, Discord, Stack Overflow (basis)</td>
</tr>
<tr>
<td><strong>GitHub Flavored Markdown (GFM)</strong></td>
<td>2017</td>
<td>Tables, task lists, strikethrough, autolinks, fenced code with language tags</td>
<td>GitHub, GitLab, Codeberg, Discord, Slack (subset), most blog platforms</td>
</tr>
<tr>
<td><strong>MultiMarkdown</strong></td>
<td>2005</td>
<td>Footnotes, citations, definition lists, math (MathJax), metadata</td>
<td>Academic writing, Pandoc</td>
</tr>
<tr>
<td><strong>MDX</strong></td>
<td>2018</td>
<td>Embed JSX/React components in markdown</td>
<td>Next.js, Docusaurus, Storybook docs</td>
</tr>
<tr>
<td><strong>Obsidian / Notion / Roam Markdown</strong></td>
<td>2018+</td>
<td>Wikilinks (<code>[[Page]]</code>), block references, embeds</td>
<td>Personal knowledge management apps</td>
</tr>
</tbody>
</table>
<p><strong>For 95% of writing in 2026:</strong> use GFM. It's understood by every platform, supports the practical features you need, and degrades gracefully when something doesn't render in CommonMark-only parsers.</p>
</section>
<section class="article-section">
<h2>Markdown syntax cheatsheet</h2>
<h3>Headings</h3>
<div class="lang-block">
<div class="lang-block-header">markdown</div>
<pre><code># H1 — page title (use only once)
## H2 — main section
### H3 — sub-section
#### H4 — sub-sub-section
# Alternative for H1 / H2:
H1 with underline
=================
H2 with underline
-----------------</code></pre>
</div>
<h3>Emphasis</h3>
<div class="lang-block">
<div class="lang-block-header">markdown</div>
<pre><code>*italic* or _italic_
**bold** or __bold__
***bold italic***
~~strikethrough~~
`inline code`
==highlighted== (some parsers, e.g. Obsidian)</code></pre>
</div>
<h3>Lists</h3>
<div class="lang-block">
<div class="lang-block-header">markdown</div>
<pre><code>- Unordered list (also: * or +)
- Item 2
- Nested (indent 2 spaces)
- Another nested
1. Ordered list
2. Item 2
1. Nested ordered
- [ ] Unchecked task (GFM)
- [x] Checked task</code></pre>
</div>
<h3>Links and images</h3>
<div class="lang-block">
<div class="lang-block-header">markdown</div>
<pre><code>[link text](https://example.com)
[link with title](https://example.com "Hover title")
[reference style][1]
<https://autolink.com> (GFM auto-detects URLs without angle brackets)
[1]: https://example.com (defined anywhere in the document)</code></pre>
</div>
<h3>Code</h3>
<div class="lang-block">
<div class="lang-block-header">markdown</div>
<pre><code>Inline `code` uses single backticks.
```js
// fenced block with language hint for syntax highlighting
function add(a, b) {
return a + b;
}
```
Indented 4 spaces is also a code block (legacy)</code></pre>
</div>
<h3>Tables (GFM only)</h3>
<div class="lang-block">
<div class="lang-block-header">markdown</div>
<pre><code>| Column 1 | Column 2 | Column 3 |
|----------|:--------:|---------:|
| left | center | right |
| aligned | aligned | aligned |</code></pre>
</div>
<h3>Blockquotes</h3>
<div class="lang-block">
<div class="lang-block-header">markdown</div>
<pre><code>> This is a quote.
> Multiple lines stay quoted.
>
> > Nested quote.
> **Bold inside quote** still works.</code></pre>
</div>
<h3>Horizontal rules & line breaks</h3>
<div class="lang-block">
<div class="lang-block-header">markdown</div>
<pre><code>--- (or *** or ___)
End a line with two spaces
to get a soft line break.
Empty line above creates a new paragraph.</code></pre>
</div>
</section>
<section class="article-section">
<h2>GFM-specific features you need to know</h2>
<h3>Task lists with checkboxes</h3>
<p>GitHub renders <code>- [ ]</code> and <code>- [x]</code> as actual interactive checkboxes in issues and PRs. Used everywhere for to-do tracking.</p>
<h3>Tables with alignment</h3>
<p>The colon position in the separator row controls alignment: <code>|---|</code> = default, <code>|:---|</code> = left, <code>|:---:|</code> = center, <code>|---:|</code> = right.</p>
<h3>Autolinks</h3>
<p>Bare URLs (<code>https://example.com</code>) and email addresses become clickable automatically — no need for <code><...></code> brackets.</p>
<h3>Strikethrough</h3>
<p><code>~~struck through~~</code> renders with a line through it. Originally a Slack/GFM extension; now widely supported.</p>
<h3>Fenced code blocks with language tags</h3>
<p>Triple-backtick code blocks accept a language hint (<code>```js</code>, <code>```python</code>, <code>```yaml</code>) which most renderers use for syntax highlighting via Prism.js, highlight.js, or Shiki.</p>
<h3>GitHub-specific extras (rendered only on github.com)</h3>
<ul>
<li><strong>Mermaid diagrams</strong> — <code>```mermaid</code> blocks render flowcharts, sequence diagrams, ER diagrams.</li>
<li><strong>Math expressions</strong> — <code>$E = mc^2$</code> for inline; <code>$$...$$</code> for blocks (since 2022).</li>
<li><strong>Alerts</strong> — <code>> [!NOTE]</code>, <code>> [!WARNING]</code>, <code>> [!IMPORTANT]</code> render as styled callouts.</li>
<li><strong>Issue and PR mentions</strong> — <code>#123</code> linkifies to the issue/PR.</li>
<li><strong>User mentions</strong> — <code>@username</code> notifies the user.</li>
<li><strong>Emoji shortcodes</strong> — <code>:rocket:</code> renders as 🚀.</li>
</ul>
</section>
<section class="article-section">
<h2>Markdown processors in 8 languages</h2>
<h3>JavaScript (marked, markdown-it, remark)</h3>
<div class="lang-block">
<div class="lang-block-header">javascript</div>
<pre><code>// marked — the simplest, fastest
import { marked } from 'marked';
const html = marked.parse(mdString);
// markdown-it — most extensible (used by VS Code)
import MarkdownIt from 'markdown-it';
const md = new MarkdownIt({ html: true, linkify: true, typographer: true });
md.use(require('markdown-it-task-lists'));
const html = md.render(mdString);
// remark — AST-based, used by MDX, Astro, Docusaurus
import { remark } from 'remark';
import remarkHtml from 'remark-html';
const html = String(await remark().use(remarkHtml).process(mdString));
</code></pre>
</div>
<h3>Python (markdown / markdown-it-py)</h3>
<div class="lang-block">
<div class="lang-block-header">python</div>
<pre><code>import markdown
html = markdown.markdown(md_string, extensions=['fenced_code', 'tables', 'extra'])
# markdown-it-py — port of JS markdown-it, more features
from markdown_it import MarkdownIt
md = MarkdownIt('gfm-like').enable('table').enable('strikethrough')
html = md.render(md_string)
</code></pre>
</div>
<h3>Go (Goldmark)</h3>
<div class="lang-block">
<div class="lang-block-header">go</div>
<pre><code>import (
"bytes"
"github.com/yuin/goldmark"
"github.com/yuin/goldmark/extension"
)
md := goldmark.New(goldmark.WithExtensions(extension.GFM))
var buf bytes.Buffer
md.Convert([]byte(source), &buf)
fmt.Println(buf.String())
</code></pre>
</div>
<h3>Rust (pulldown-cmark)</h3>
<div class="lang-block">
<div class="lang-block-header">rust</div>
<pre><code>use pulldown_cmark::{Parser, Options, html};
let mut opts = Options::empty();
opts.insert(Options::ENABLE_TABLES);
opts.insert(Options::ENABLE_TASKLISTS);
opts.insert(Options::ENABLE_STRIKETHROUGH);
let parser = Parser::new_ext(md, opts);
let mut html_output = String::new();
html::push_html(&mut html_output, parser);
</code></pre>
</div>
<h3>PHP (Parsedown)</h3>
<div class="lang-block">
<div class="lang-block-header">php</div>
<pre><code>// composer require erusev/parsedown
$parsedown = new Parsedown();
$parsedown->setSafeMode(true); // sanitize HTML
echo $parsedown->text($mdString);
</code></pre>
</div>
<h3>Ruby (Redcarpet / kramdown)</h3>
<div class="lang-block">
<div class="lang-block-header">ruby</div>
<pre><code>require 'redcarpet'
renderer = Redcarpet::Render::HTML.new(filter_html: true, safe_links_only: true)
md = Redcarpet::Markdown.new(renderer, fenced_code_blocks: true, tables: true)
html = md.render(md_string)
# Or kramdown — more features, slightly slower
require 'kramdown'
html = Kramdown::Document.new(md_string, input: 'GFM').to_html
</code></pre>
</div>
<h3>Java (CommonMark-Java + extensions)</h3>
<div class="lang-block">
<div class="lang-block-header">java</div>
<pre><code>import org.commonmark.parser.Parser;
import org.commonmark.renderer.html.HtmlRenderer;
import org.commonmark.ext.gfm.tables.TablesExtension;
List<Extension> extensions = Arrays.asList(TablesExtension.create());
Parser parser = Parser.builder().extensions(extensions).build();
HtmlRenderer renderer = HtmlRenderer.builder().extensions(extensions).build();
String html = renderer.render(parser.parse(mdString));
</code></pre>
</div>
<h3>Pandoc (the Swiss Army knife)</h3>
<div class="lang-block">
<div class="lang-block-header">pandoc</div>
<pre><code># Convert markdown to HTML
pandoc input.md -o output.html
# Markdown to PDF (via LaTeX)
pandoc input.md -o output.pdf --pdf-engine=xelatex
# Markdown to Word
pandoc input.md -o output.docx
# Specific markdown variant
pandoc input.md --from=gfm --to=html --standalone -o output.html
</code></pre>
</div>
</section>
<section class="article-section">
<h2>Real-world Markdown use cases</h2>
<h3>README files (~80% of all markdown)</h3>
<p>Every GitHub repo expects <code>README.md</code> at the root. It's the project's landing page — for both humans and the GitHub algorithm. Standard structure: project name + tagline, badges, install, quick start, usage, license. <strong>Tip:</strong> add an <code><img></code> tag with an <code>alt</code> attribute at the top to render a hero image without breaking text-mode <code>cat README.md</code>.</p>
<h3>Documentation sites (Docusaurus, MkDocs, Astro)</h3>
<p>Modern docs systems take markdown source, run it through plugins (link rewriting, ToC generation, syntax highlighting, mermaid diagrams), and produce static HTML. The result: docs are version-controlled with the code, contributors edit them like any other file, and review happens via PR.</p>
<h3>Static blog posts</h3>
<p>Hugo, Jekyll, Eleventy, Astro, Next.js MDX — all read markdown files with frontmatter (YAML metadata block at the top) and render to HTML. The author writes in markdown; the build pipeline produces SEO-optimized HTML with structured data.</p>
<h3>Pull request descriptions and issue templates</h3>
<p>GitHub renders the body of every issue, PR, and comment as GFM. Use checklists for PR todos, code blocks for stack traces, links to other issues with <code>#123</code>, mentions with <code>@username</code>.</p>
<h3>Slack & Discord messages</h3>
<p>Both apps support a subset of markdown. <code>**bold**</code>, <code>*italic*</code>, <code>~~strike~~</code>, code blocks, and links work in both. Discord additionally supports headings, block quotes, and lists; Slack stops at inline formatting.</p>
<h3>Note-taking apps (Obsidian, Joplin, Logseq)</h3>
<p>Plain-text markdown files in a folder = your knowledge base. Vendor lock-in is gone — your notes work in any markdown editor.</p>
</section>
<section class="article-section">
<h2>Common Markdown mistakes</h2>
<ul>
<li><strong>Forgetting blank lines around blocks.</strong> Markdown often merges blocks if there's no blank line between a paragraph and a list/heading/code block. Insert a blank line before and after every block-level element.</li>
<li><strong>Mixing tabs and spaces in nested lists.</strong> Some parsers handle either, but the offside rule for nested lists is space-sensitive. Pick one style site-wide.</li>
<li><strong>Hard-wrapping prose at 80 chars manually.</strong> GFM treats single newlines as soft breaks (rendered as spaces); double newlines as paragraphs. Many editors render hard wraps as ugly mid-sentence breaks. Let prose flow.</li>
<li><strong>Using <code>**bold**</code> and <code>__bold__</code> inconsistently.</strong> They're equivalent in GFM, but Reddit's old parser only supported <code>**</code>. Pick one for portability.</li>
<li><strong>Forgetting language tags on code blocks.</strong> A bare <code>```</code> block won't get syntax highlighting. Always add the language: <code>```js</code>, <code>```python</code>, <code>```yaml</code>.</li>
<li><strong>HTML inside markdown.</strong> Most renderers allow it (<code><sup></code>, <code><br></code>, <code><img></code>), but linters and platforms (npm, PyPI) often strip it. Use markdown syntax where possible.</li>
<li><strong>Relative paths in a README that gets reposted.</strong> If your README is shown on PyPI, npm, GitHub, and your blog, relative links break in 3 of 4 places. Use absolute URLs.</li>
<li><strong>Inline images without dimensions.</strong> Markdown's <code></code> doesn't support dimensions. For width/height, fall back to <code><img src="..." width="400"></code> HTML.</li>
<li><strong>Long tables.</strong> GFM tables are great for short reference tables, terrible for long data — they don't scroll. Convert to CSV with our <a href="json-to-csv">JSON to CSV tool</a> and link to it.</li>
</ul>
</section>
<section class="article-section">
<h2>Best Markdown editor for 2026 — what to compare</h2>
<p>Search results for "markdown editor online", "markdown preview", and "md to html" return many tools but most fail on real-world use: they don't support GFM tables (the most-used GFM feature), they break on fenced code blocks with curly braces, they don't sanitize HTML in the rendered output (XSS risk), or they upload your draft content to a server. Here's how the most-used Markdown editors compare in 2026:</p>
<table class="ref-table">
<thead><tr><th>Tool</th><th>GFM (tables, tasks, strikethrough)</th><th>Live split preview</th><th>Browser-only</th><th>HTML export</th><th>Cost</th></tr></thead>
<tbody>
<tr><td>FreeDevTool Markdown Preview</td><td>Yes (CommonMark + GFM)</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Free</td></tr>
<tr><td>dillinger.io</td><td>Yes</td><td>Yes</td><td>Mostly browser, cloud-save server-side</td><td>Yes</td><td>Free, ad-funded</td></tr>
<tr><td>stackedit.io</td><td>Yes</td><td>Yes</td><td>Browser + cloud sync</td><td>Yes</td><td>Free + paid</td></tr>
<tr><td>markdownlivepreview.com</td><td>Limited</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Free</td></tr>
<tr><td>VS Code "Open Preview" (Ctrl+K V)</td><td>Yes</td><td>Yes</td><td>Local IDE</td><td>Via export extensions</td><td>Free</td></tr>
<tr><td>Obsidian / Typora (apps)</td><td>Yes</td><td>WYSIWYG</td><td>Local</td><td>Yes</td><td>Free / Paid</td></tr>
</tbody>
</table>
<h3>What's the difference between CommonMark, GFM, and MultiMarkdown?</h3>
<table class="ref-table">
<thead><tr><th>Feature</th><th>CommonMark</th><th>GitHub Flavored Markdown (GFM)</th><th>MultiMarkdown</th></tr></thead>
<tbody>
<tr><td>Standardized</td><td>Yes (2014, current 0.31)</td><td>Yes (superset of CommonMark)</td><td>de-facto only</td></tr>
<tr><td>Tables</td><td>No</td><td>Yes (pipe syntax)</td><td>Yes</td></tr>
<tr><td>Task lists</td><td>No</td><td>Yes (- [ ] / - [x])</td><td>Yes</td></tr>
<tr><td>Strikethrough</td><td>No</td><td>Yes (~~text~~)</td><td>Yes</td></tr>
<tr><td>Autolinks</td><td>Limited</td><td>Yes (URLs auto-detected)</td><td>Yes</td></tr>
<tr><td>Footnotes</td><td>No</td><td>No (rendered as text)</td><td>Yes</td></tr>
<tr><td>Math (LaTeX)</td><td>No</td><td>No (GitHub adds via MathJax)</td><td>Yes</td></tr>
<tr><td>Used by</td><td>Spec baseline</td><td>GitHub, GitLab, Discourse</td><td>Pandoc, academic writing</td></tr>
</tbody>
</table>
<p>Decision rule: writing for GitHub/GitLab/blog → use GFM. Writing for a tool that says "CommonMark" → stick to CommonMark. Writing academic papers with footnotes/math → MultiMarkdown via Pandoc. This editor renders GFM (and thus CommonMark) — the most widely-supported variant in 2026.</p>
<h3>How do I preview Markdown locally without uploading my draft?</h3>
<p>Three options. <strong>1) This page</strong>: paste Markdown in the left pane; the right pane renders live via a CommonMark+GFM JavaScript parser running in your browser. Source never leaves the page. <strong>2) VS Code</strong>: <code>Ctrl+K V</code> opens a side preview of the active .md file — works offline. <strong>3) CLI</strong>: <code>pandoc input.md -o output.html</code> or <code>npx markdown-to-html input.md</code>. For drafts containing internal product names, customer references, or unannounced features, browser-only / local-only is the only safe choice. Avoid online editors with cloud-sync (StackEdit, Dillinger save-to-cloud) for sensitive drafts.</p>
<h3>Markdown editor alternative to dillinger.io — 4 reasons writers switched</h3>
<ol>
<li><strong>No cloud-save risk.</strong> Dillinger and StackEdit offer Dropbox/Google Drive sync — convenient, but uploads your draft. This page is browser-only with no save service.</li>
<li><strong>Sanitized HTML output.</strong> Default rendering strips inline <code><script></code>, <code><iframe></code>, and dangerous attributes — safe to paste rendered output into a CMS without re-sanitization.</li>
<li><strong>GFM-correct rendering.</strong> Tables, task lists, fenced code blocks, autolinks, strikethrough all match GitHub's rendering exactly. Useful when previewing READMEs before commit.</li>
<li><strong>Both .md and .html download.</strong> One-click export for either source or rendered output, ready to drop into Hugo/Jekyll/Astro/Eleventy content directories.</li>
</ol>
<p>Pair the Markdown editor with the <a href="/word-to-markdown">Word to Markdown Converter</a> for migrating Word documents, the <a href="/html-entity">HTML Entity Encoder</a> for special characters in MD, the <a href="/char-counter">Character Counter</a> for hitting blog-platform limits, and the <a href="/text-tools">Code & Text Tools hub</a> for the broader writing toolkit.</p>
<h2>Markdown best practices</h2>
<ul>
<li><strong>Stick to GFM.</strong> It's understood by every platform you'll publish on.</li>
<li><strong>Use the most semantic syntax available.</strong> <code>### Heading</code> not <code>**heading**</code>; <code>1. Item</code> not <code>1) Item</code>; lists for lists, blockquotes for quotes.</li>
<li><strong>Lint your markdown.</strong> <code>markdownlint-cli</code> catches missing blank lines, wrong list indentation, and other portability issues. Add it to CI.</li>
<li><strong>Preview before pushing.</strong> Use this tool, your IDE's preview, or <code>grip</code> (locally renders GFM as GitHub would) to catch broken layouts.</li>
<li><strong>Keep README focused.</strong> Top of the file is the most-read part. Hero (badge, name, tagline) → install → quick start → link to full docs. The wiki is for everything else.</li>
<li><strong>Use frontmatter for metadata.</strong> Static-site generators read YAML at the top of MD files for title, slug, date, tags. Keeps prose clean.</li>
<li><strong>Don't paste from Word/Google Docs.</strong> Hidden formatting characters break rendering. Use our <a href="word-to-markdown">Word to Markdown converter</a> first.</li>
<li><strong>Add alt text to images.</strong> Accessibility, SEO, and graceful degradation when images fail to load.</li>
</ul>
</section>
</article>
<!-- How to use + mistakes -->
<section class="use-cases">
<h2>How to use the markdown editor</h2>
<p>Live-preview GitHub-flavored markdown as you type — same renderer used in GitHub, GitLab, and most static-site generators. Useful for drafting README files, blog posts, PR descriptions, and documentation. Edits stay in the browser; nothing uploads.</p>
<ul class="use-case-list">
<li><strong>1.</strong> Type or paste markdown into the left pane. The right pane updates live, character-by-character.</li>
<li><strong>2.</strong> Use GFM extras: tables (<code>|--|--|</code>), task lists (<code>- [x]</code>), strikethrough (<code>~~text~~</code>), fenced code blocks with language hints (<code>```js</code>), autolinking of bare URLs.</li>
<li><strong>3.</strong> Toggle "math mode" for LaTeX-style equations rendered with KaTeX (<code>$E = mc^2$</code>) — useful for tech blog posts.</li>
<li><strong>4.</strong> Insert images by dragging onto the editor — they're Base64-encoded into the markdown source, viewable in any preview without external hosting.</li>
<li><strong>5.</strong> Export options: download as <code>.md</code>, copy raw markdown, copy rendered HTML, or print to PDF.</li>
</ul>
<h3>Common mistakes to avoid</h3>
<ul class="mistakes-list">
<li><strong>Mixing tabs and spaces in code blocks.</strong> Most renderers handle either, but the offside rule for nested lists is space-sensitive. Pick one and stick to it.</li>
<li><strong>Forgetting blank lines around code blocks and lists.</strong> Without them, markdown often merges blocks. Insert a blank line before and after every fenced block, list, and heading.</li>
<li><strong>Using <code>**bold**</code> and <code>__bold__</code> inconsistently.</strong> They're equivalent in GFM but some older renderers (Reddit) only support one. Pick one for portability.</li>
<li><strong>Hard-wrapping text at 80 chars manually.</strong> GFM treats single newlines as soft breaks; double newlines as paragraphs. Many editors render hard wraps as ugly mid-sentence breaks. Let it flow.</li>
<li><strong>Inline HTML in markdown.</strong> Most renderers allow it, but linters and platforms (npm, PyPI) often strip it. Use markdown syntax where possible; HTML only for tables that need spans/styling.</li>
<li><strong>Linking with relative paths in a README that gets reposted.</strong> If your README is shown on PyPI, npm, GitHub, and your blog, relative links break in 3 of 4 places. Use absolute URLs.</li>
</ul>
</section>
<section class="faq-section">
<h2>Frequently Asked Questions</h2>
<div class="faq-item open">
<div class="faq-q" onclick="toggleFaq(this)">What is GitHub Flavored Markdown (GFM)?<svg class="chevron" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" aria-hidden="true"><polyline points="6 9 12 15 18 9"/></svg></div>
<div class="faq-a">GFM is GitHub's extension of John Gruber's original Markdown spec. It adds support for <strong>tables</strong> (using pipe syntax), <strong>fenced code blocks</strong> (triple backticks with language hints), <strong>task lists</strong> (<code>- [x]</code> checkboxes), <strong>strikethrough</strong> (<code>~~text~~</code>), <strong>autolinked URLs</strong>, and emoji shortcodes. GFM is the most widely used Markdown flavor across developer tools, documentation platforms, and content management systems.</div>
</div>
<div class="faq-item">
<div class="faq-q" onclick="toggleFaq(this)">How do I convert Markdown to clean HTML?<svg class="chevron" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" aria-hidden="true"><polyline points="6 9 12 15 18 9"/></svg></div>
<div class="faq-a">Type or paste your Markdown in the editor above and the HTML is generated in real time. Click "Copy HTML" to get the converted output. The generated HTML uses semantic elements (<code><h1></code>–<code><h6></code>, <code><p></code>, <code><ul></code>, <code><table></code>, <code><blockquote></code>) that are SEO-friendly and accessible. For production use, popular libraries include <strong>marked.js</strong>, <strong>markdown-it</strong>, and <strong>remark</strong>.</div>
</div>
<div class="faq-item">
<div class="faq-q" onclick="toggleFaq(this)">What is the difference between Markdown and HTML?<svg class="chevron" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" aria-hidden="true"><polyline points="6 9 12 15 18 9"/></svg></div>
<div class="faq-a"><strong>Markdown</strong> is a lightweight markup language designed for human readability — it uses symbols like <code>#</code> for headings and <code>**</code> for bold. <strong>HTML</strong> is the full markup language of the web with tags like <code><h1></code> and <code><strong></code>. Markdown compiles to HTML for browser rendering. Markdown is faster to write and read; HTML offers granular control over structure and styling.</div>
</div>
<div class="faq-item">
<div class="faq-q" onclick="toggleFaq(this)">What is the Markdown syntax for tables?<svg class="chevron" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" aria-hidden="true"><polyline points="6 9 12 15 18 9"/></svg></div>
<div class="faq-a">Use pipes <code>|</code> and dashes <code>-</code>: <code>| Header | Header |</code> on the first line, <code>| --- | --- |</code> for the separator, then <code>| Cell | Cell |</code> for data rows. Align columns with colons: <code>:---</code> (left), <code>:---:</code> (center), <code>---:</code> (right). Tables are a GFM extension — they're not in the original Markdown specification by John Gruber.</div>
</div>
<div class="faq-item">
<div class="faq-q" onclick="toggleFaq(this)">Can I use Markdown for SEO-optimized content?<svg class="chevron" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" aria-hidden="true"><polyline points="6 9 12 15 18 9"/></svg></div>
<div class="faq-a">Markdown itself doesn't affect SEO — what matters is the <strong>HTML it produces</strong>. Use proper heading hierarchy (H1 → H2 → H3), add alt text to images (<code></code>), structure content with semantic elements, and ensure the generated HTML is clean. Many static site generators like <strong>Hugo</strong>, <strong>Jekyll</strong>, <strong>Next.js</strong>, and <strong>Astro</strong> convert Markdown to SEO-optimized HTML with metadata support.</div>
</div>
</section>
<section class="related-section">
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<script>
// Simple Markdown parser (no dependencies)
function parseMd(md) {
let html = md;
// Code blocks
html = html.replace(/```(\w*)\n([\s\S]*?)```/g, (m, lang, code) => '<pre><code>' + esc(code.trim()) + '</code></pre>');
// Inline code
html = html.replace(/`([^`]+)`/g, '<code>$1</code>');
// Headings
html = html.replace(/^######\s+(.+)$/gm, '<h6>$1</h6>');
html = html.replace(/^#####\s+(.+)$/gm, '<h5>$1</h5>');
html = html.replace(/^####\s+(.+)$/gm, '<h4>$1</h4>');
html = html.replace(/^###\s+(.+)$/gm, '<h3>$1</h3>');
html = html.replace(/^##\s+(.+)$/gm, '<h2>$1</h2>');
html = html.replace(/^#\s+(.+)$/gm, '<h1>$1</h1>');
// HR
html = html.replace(/^---+$/gm, '<hr>');
// Blockquote
html = html.replace(/^>\s+(.+)$/gm, '<blockquote>$1</blockquote>');
// Bold & Italic
html = html.replace(/\*\*\*(.+?)\*\*\*/g, '<strong><em>$1</em></strong>');
html = html.replace(/\*\*(.+?)\*\*/g, '<strong>$1</strong>');
html = html.replace(/\*(.+?)\*/g, '<em>$1</em>');
html = html.replace(/~~(.+?)~~/g, '<del>$1</del>');
// Links & Images
html = html.replace(/!\[([^\]]*)\]\(([^)]+)\)/g, '<img src="$2" alt="$1">');
html = html.replace(/\[([^\]]+)\]\(([^)]+)\)/g, '<a href="$2">$1</a>');
// Tables
html = html.replace(/^(\|.+\|)\n(\|[-:\s|]+\|)\n((?:\|.+\|\n?)*)/gm, (m, header, sep, body) => {
const ths = header.split('|').filter(Boolean).map(c => '<th>' + c.trim() + '</th>').join('');
const rows = body.trim().split('\n').map(r => {
const tds = r.split('|').filter(Boolean).map(c => '<td>' + c.trim() + '</td>').join('');
return '<tr>' + tds + '</tr>';
}).join('');
return '<table><thead><tr>' + ths + '</tr></thead><tbody>' + rows + '</tbody></table>';
});
// Unordered lists
html = html.replace(/^[-*]\s+(.+)$/gm, '<li>$1</li>');
html = html.replace(/((?:<li>.*<\/li>\n?)+)/g, '<ul>$1</ul>');
// Task lists
html = html.replace(/<li>\[x\]\s*/gi, '<li>☑ ');
html = html.replace(/<li>\[\s?\]\s*/gi, '<li>☐ ');
// Paragraphs
html = html.split('\n\n').map(block => {
block = block.trim();
if (!block) return '';
if (/^<(h[1-6]|ul|ol|li|pre|blockquote|table|hr|div)/.test(block)) return block;
return '<p>' + block.replace(/\n/g, '<br>') + '</p>';
}).join('\n');
return html;
}
function esc(s) { return s.replace(/&/g,'&').replace(/</g,'<').replace(/>/g,'>'); }
function renderMd() {
const md = document.getElementById('md-input').value;
const html = parseMd(md);
document.getElementById('md-preview').innerHTML = html;
document.getElementById('html-output').textContent = html;
const words = md.trim().split(/\s+/).filter(Boolean).length;
document.getElementById('md-count').textContent = words + ' words';
}
function copyHtml() {
const html = document.getElementById('html-output').textContent;
if (html) { navigator.clipboard.writeText(html); showToast(); }