Best Online Markdown Viewers & Editors, Tested (2026)
Most “best Markdown editor” lists repeat each tool’s marketing. We pasted the same document into six free online tools, and checked what rendered, whether our text left the browser, and whether each worked on a phone.
Disclosure: we make MarkdownPreview.net, which is one of the six tools. We ran it through the same test as the others and report where it is not the right choice.
For previewing GitHub-style Markdown, the tools that rendered everything in our test document (tables, alerts, math, footnotes, code, Mermaid) were MarkdownPreview.net and HackMD. HackMD was the only one that stored our text on its servers. StackEdit and Dillinger rendered most things but showed GitHub alerts as plain quotes; Dillinger also shows Mermaid as code.
Results at a glance
Tested October 11, 2026 with the same document (shown under “How we tested”). A result describes what we saw with default settings; a feature that needs a setting we didn’t find would show as “No”.
| Feature | MarkdownPreview.net | Dillinger | StackEdit | HackMD | markdownlivepreview.com | markdownviewer.dev |
|---|---|---|---|---|---|---|
| Preview without signing in | Yes | Yes | Yes | Guest note (hackmd.io/new) | Yes | Yes |
| Tables | Yes | Yes | Yes | Yes | Yes | Yes |
| Task-list checkboxes | Yes | Yes | Yes | Yes | Shown, disabled | Shown, disabled |
| GitHub alert ([!NOTE]) as a callout | Yes | No | No | Yes | No | No |
| Math (inline and block) | Yes | Yes | Yes | Yes | No | No |
| Footnotes | Yes | Yes | Yes | Yes | No | No |
| Syntax-highlighted code | Yes | Yes | Yes | Yes | No | Yes |
| Mermaid diagrams | Yes | No | Yes | Yes | Yes | Yes |
| Open a local .md file | Yes | Yes | Yes | No file picker found | Yes | No picker found |
| Our text stayed in the browser | Yes | Yes | Yes | No | Yes | Yes |
Where does your text go?
After typing a unique marker string, we watched every network request and WebSocket message for 20 seconds. Only HackMD sent the text to a server. Hosts below are third parties each tool contacted when loading; being listed does not mean they received your text.
| Tool | Where the text is kept | Third-party hosts contacted |
|---|---|---|
| MarkdownPreview.net | Browser only (autosaved locally) | Google Tag Manager and Google Analytics (visit counts only; not loaded on share links) |
| Dillinger | Browser local storage | BuySellAds, DoubleClick, placehold.co, jsDelivr |
| StackEdit | Not determined (not found in local storage); no content sent while typing | apis.google.com (cloud sync requires Google sign-in) |
| HackMD | On HackMD's servers — every edit is sent over a WebSocket | Many, including Google Tag Manager, Google Analytics, DoubleClick, customer.io, Plausible, Sentry, and Tally |
| markdownlivepreview.com | Browser local storage | Google Tag Manager and Google Analytics |
| markdownviewer.dev | Browser local storage | Ahrefs analytics, Cloudflare Insights, jsDelivr, cdnjs, Google Fonts |
Which one should you use?
- Checking how a README or doc will look on GitHub: MarkdownPreview.net rendered all seven features, including GitHub alerts, with nothing sent to a server. Its GitHub Markdown preview can load a public README by URL.
- Notes you want stored online and shared by link: HackMD rendered everything and works as a guest, but it stores the document on its servers, so avoid confidential text.
- Cloud sync and publishing: StackEdit offers sync and publishing through a Google sign-in, which we did not test further. MarkdownPreview.net has no accounts or cloud sync by design.
- A simple editor with several export formats: Dillinger exports Markdown, HTML, styled HTML, and PDF, but showed Mermaid as code and GitHub alerts as plain quotes, and its preview did not appear on a phone.
- The most minimal viewer: markdownlivepreview.com and markdownviewer.dev are quick for basic Markdown, but neither rendered math, footnotes, or alerts in our test.
Notes on each tool
- MarkdownPreview.net: rendered every feature; opened a local file via Open File; exports Markdown, HTML, PDF (through your browser’s print dialog), and PNG, and copies rich text. Loads Google Analytics for visit counts, but not when you open a share link.
- Dillinger: loads straight into an editor. A Google Cloud ad strip sits at the bottom. Text is kept in local storage.
- StackEdit: a “new StackEdit 5” tour balloon covered part of the preview until we clicked Skip. Its PDF and Pandoc exports are labeled “sponsor”.
- HackMD: the home page is marketing only;
hackmd.io/newopens a guest note. Banners and sign-in prompts appear over the editor. It was the only tool that rendered GitHub alerts besides ours. - markdownlivepreview.com: a clean interface with no banners. Its PDF export button produced no download in our test (not determined why).
- markdownviewer.dev: advertises LaTeX/KaTeX, but math stayed raw text in our test, including in its own welcome document. Exports Markdown, styled HTML, and PDF.
On a phone
Tested at a 390 × 844 px viewport.
| MarkdownPreview.net | Opens in a full-width reading view; Edit switches to the editor. No horizontal scrolling. |
| Dillinger | Only the editor was usable at 390 px wide; the preview never appeared. |
| StackEdit | Single pane with icons to switch between editor, split, and preview; math and diagrams fit. |
| HackMD | Single pane with an eye icon to toggle the preview; no horizontal overflow. |
| markdownlivepreview.com | Editor and preview side by side, each very narrow; the toolbar overflows slightly. |
| markdownviewer.dev | Editor and Preview tabs at the bottom work; a floating toolbar overlaps the page bottom. |
On October 11, 2026 we used headless Chromium 141 (Playwright) on Linux with a fresh browser profile for each tool, at 1280 × 800 for desktop and 390 × 844 for mobile. We pasted the test document into each editor from the clipboard, typed a unique marker string, and recorded all requests and WebSocket messages for 20 seconds. Local files were opened through each tool’s own file chooser where one existed.
Limits: we tested default settings only, pasted rather than typed the document, and used synthetic drag-and-drop events (not real operating-system drags) where no file picker existed. We picked the last two tools from search results for “markdown viewer online”, not an exhaustive survey. Tools change — email hello@markdownpreview.net if something here is out of date. We also created several guest test notes on hackmd.io while testing.
# Heading
A paragraph with **bold**, *italic*, ~~strike~~ and a [link](https://example.com).
| A | B |
|---|---|
| 1 | 2 |
- [x] done task
- [ ] open task
> [!NOTE]
> GitHub alert syntax
Inline math $E=mc^2$ and block:
$$\int_0^1 x^2\,dx = \tfrac13$$
Footnote ref[^1].
[^1]: The footnote.
```js
console.log("hi")
```
```mermaid
flowchart LR
A --> B
```Frequently asked questions
What is the best free online Markdown viewer?
Which online Markdown editors render Mermaid diagrams?
Which online Markdown editors support math?
Which online Markdown viewers keep my text private?
Which GitHub features do online Markdown viewers miss most often?
Can I open a local .md file in these tools?
Tools tested
- MarkdownPreview.net — our tool — disclosed
- Dillinger
- StackEdit
- HackMD
- markdownlivepreview.com
- markdownviewer.dev
Looking for an editor’s built-in preview instead? See how to preview Markdown in any editor, or read 6 ways to preview Markdown in a browser.