Almost every tool that calls itself a Markdown editor or converter does the basics: heading, bold, italic, lists, links. Where they differ is in the details: how they handle GFM tables and task lists, whether they round-trip cleanly from HTML back to Markdown, whether the live preview is accurate, and what they do with your content (most upload it). We tested six free Markdown converters with the same sample document and ranked them on what actually matters in real workflows.
Our pick
Bidirectional (Markdown↔HTML), full GFM support, live preview, runs entirely in your browser. Combines a clean two-pane UI with the privacy story most converters cannot match.
How we tested
Each tool received the same Markdown sample containing headings, bold and italic, links, lists, a table, a task list, an inline code snippet, a fenced code block, a blockquote, and a horizontal rule. We then converted the rendered HTML back to Markdown to see how clean the round-trip was. Measured: feature coverage, conversion accuracy, UI quality, and privacy posture.
How we scored
Each tool was scored out of 10: feature coverage and GFM support (3 points), conversion accuracy (3 points), UI quality (2 points), privacy (2 points).
The full ranking
Rank #1
ToolHub Markdown Converter
Bidirectional conversion, full GFM (tables, task lists, strikethrough, fenced code), live preview with toggleable code view, runs entirely in your browser. Round-tripped the test document with no detail lost. The only entry in the comparison with a verifiable no-upload privacy story.
Pros
- Markdown to HTML and HTML to Markdown in the same tool
- Full GFM support (tables, task lists, strikethrough)
- Live preview with code/preview toggle
- 100% client-side, content never uploaded
- Sample loader and clear/swap helpers
- Free with no signup, no quota, no watermark
Cons
- No syntax highlighting in code blocks (yet)
- No file save (output is meant to be copied)
Rank #2
Dillinger
Long-running open-source Markdown editor with a polished split-pane UI and good GFM support. Cloud sync to Dropbox, Google Drive, etc. The tool itself runs in the browser but the cloud features upload your content.
Pros
- Polished split-pane editor
- Cloud sync integrations
- Open source
- Strong GFM support
Cons
- Cloud features require account and uploads
- Heavy first load
- Not focused on round-trip conversion
Rank #3
StackEdit
Feature-rich Markdown editor with KaTeX math support and document organization. Good for long-form writing in Markdown. Cloud sync uploads content.
Pros
- Math support via KaTeX
- Document organization
- GFM support
Cons
- Cloud features upload content
- UI is dense for casual use
- Account required for sync
Rank #4
markdown-it Demo
The official demo for the markdown-it library. Excellent conversion accuracy and purely client-side. UI is bare-bones (it is a demo), no HTML to Markdown, no sample, no preview toggle.
Pros
- Best CommonMark+GFM conversion fidelity in this list
- Purely client-side
- Open source library you can self-host
Cons
- Demo UI, not really a finished tool
- Markdown to HTML only (one direction)
- No copy button
Rank #5
HTML to Markdown (turndown demo)
The demo for the turndown library, the standard HTML to Markdown converter. Does its one direction well. Bare UI, no Markdown to HTML.
Pros
- Best HTML to Markdown conversion in the list
- Purely client-side
- Powers most other HTML to Markdown tools
Cons
- Demo UI
- One-way only (HTML to Markdown)
- No live preview, no sample
Rank #6
Online Markdown Editor (markdownlivepreview.com)
Simple side-by-side preview tool. Works fine for casual use. No HTML to Markdown direction, ads on the page, basic GFM support.
Pros
- Simple split view
- Markdown rendering works correctly
Cons
- Markdown to HTML only
- Ads on the page
- Basic feature set
Side by side
| Feature | ToolHub | Dillinger | StackEdit | markdown-it | turndown demo |
|---|---|---|---|---|---|
| Markdown to HTML | Yes | Yes | Yes | Yes | No |
| HTML to Markdown | Yes | No | No | No | Yes |
| Live preview | Yes | Yes | Yes | Partial | No |
| GFM tables | Yes | Yes | Yes | Yes | Yes |
| Task lists | Yes | Yes | Yes | Yes | Yes |
| Stays on device | Yes | Partial | Partial | Yes | Yes |
| No signup | Yes | Partial | Partial | Yes | Yes |
| Sample / copy buttons | Yes | Yes | Yes | No | No |
What makes a converter accurate
Markdown looks simple but the spec has many edge cases that different processors handle differently. Tests we ran on the sample document:
Round-trip fidelity
Convert Markdown to HTML, then HTML back to Markdown. If the result matches the original, the converter pair has high fidelity. ToolHub round-tripped our sample with formatting preserved. Most other tools either had no reverse direction or lost task list states and table alignment.
GFM tables
Tables are the most-broken feature in casual Markdown renderers. The header divider row, alignment colons, and cell escaping all have edge cases. Top tools (ToolHub, Dillinger, StackEdit, markdown-it) handle these correctly. Older or simpler tools often do not.
Task lists
Checked boxes [x] and unchecked [ ] should render as actual checkboxes. All five ranked tools handle this. The bottom-tier converters sometimes leave them as raw brackets.
Inline HTML
Standard Markdown allows raw HTML inside the source. A good converter passes inline HTML through unchanged. ToolHub, Dillinger, and StackEdit all do this. Some stricter converters strip or escape it.
Who should pick which
For one-off conversions: ToolHub Markdown Converter
Need to convert a README to HTML for an email, or paste cleaned-up HTML from a web page into your notes as Markdown? ToolHub does both directions in one tool, runs locally, no signup. The simplest workflow.
For long-form writing: Dillinger or StackEdit
If you are writing a book chapter, technical documentation, or a long blog post in Markdown and want sync across devices, Dillinger or StackEdit are the right tools. Just understand the cloud features upload your content.
For self-hosted conversion: markdown-it or turndown
These are open-source libraries powering most of the modern Markdown ecosystem. If you want to add Markdown rendering to your own app, install one of these directly and skip the web tools entirely.
For VS Code users: built-in or any Markdown extension
VS Code renders Markdown previews natively for any .md file. Press Cmd+K then V to open the preview pane. Saves you the context switch to a web tool for files you are already editing.
Common questions
Does converter choice matter for my published content?
For most blog and README content, no. All major converters produce equivalent HTML for standard syntax. Differences show up in edge cases: deeply nested lists, complex tables, inline HTML mixed with Markdown. For those, accuracy matters.
Can I use a Markdown library in my own code?
Yes. marked and markdown-it are the most popular for JavaScript. Both are well-maintained, small, and work in browsers and Node. ToolHub uses marked for Markdown to HTML and turndown for the reverse.
How do I sanitize Markdown from untrusted users?
Convert Markdown to HTML, then sanitize the HTML with DOMPurify or rehype-sanitize before rendering. Markdown allows inline HTML by default, which is an XSS vector if the source is user-supplied.
When to use a converter vs an editor
Final word
For day-to-day Markdown to HTML and HTML to Markdown conversion that respects your content, ToolHub Markdown Converter is the strongest free option available right now. For long-form writing and document management, Dillinger and StackEdit are still solid (with the cloud trade-off). For embedding Markdown rendering in your own code, install the marked or markdown-it library directly.