Open testing / Practical documentation

Markdown Compatibility Lab

Can a Markdown editor render a realistic technical document? Try a downloadable, reusable fixture that combines a table, fenced code, Mermaid diagram and KaTeX equation. Compare results yourself instead of trusting feature badges.

Download the test Markdown (.md) ↓ Open Markups editor → Markdown cheatsheet

Updated 23 October 2026 · Reproducible example · No registration

What the fixture covers

The same source file exercises a realistic API design note. It intentionally uses a small subset of Markdown so it can be inspected in other editors too.

  • CommonMark-style elements: headings, paragraphs, task list, emphasis, blockquote and a fenced JSON/JavaScript example.
  • GitHub-flavored table: header cells, alignment and three rows.
  • Mermaid: a four-node flowchart inside a mermaid code fence.
  • KaTeX: inline and block LaTeX math with a fraction.
  • Export QA: format-specific manual checks; visual similarity alone is not a fidelity guarantee.

View the plain-text test fixture. It is a real public .md asset, not a screenshot or generated testimonial.

1. Verify the Markdown table

After pasting the fixture, check that the preview shows three columns and an aligned numeric column. Also check the task-list checkboxes and code highlighting.

| Field | Type | Required |
| :--- | :--- | :---: |
| request_id | string | Yes |
| elapsed_ms | number | Yes |

2. Verify the Mermaid diagram

The flowchart should show Write Markdown → Render preview → Visual check → Export, with a loop back to editing when changes are needed.

```mermaid
flowchart LR
  A[Write Markdown] --> B[Render preview]
  B --> C{Visual check}
  C -->|Pass| D[Export]
  C -->|Adjust| A
```

3. Verify the KaTeX math

Check that the preview typesets an inline fraction and a centered display equation, rather than showing raw dollar signs. If math rendering is turned off, behavior can differ between editors.

Inline: $r = \frac{n_{\mathrm{done}}}{n_{\mathrm{total}}}$

Display:
$$
\mathrm{estimated\_time} = \frac{N \times t}{60}
$$

4. Test the actual exported files

  1. Download the fixture and open the Markups editor. Import or paste the entire text. Wait for Mermaid and math rendering to finish.
  2. Download the source as .md. Reopen it in a text editor; code fences, LaTeX source and table delimiters should remain editable.
  3. Export HTML. Open the resulting file and compare it with the preview, including Mermaid and math if present.
  4. Export a PDF. Inspect diagrams and page breaks and test whether you can select a sentence. Markups currently generates an image-based PDF, not a searchable/selectable text PDF.
  5. Try the Word export if needed. The output is HTML with a .doc filename and is not a native .docx file.

Large tables, fonts, long documents, cross-origin media and browser differences can affect output. Test your real document before relying on any exported format.

Compatibility is not a universal pass/fail claim

Different Markdown implementations support different extensions. A Mermaid block may be ordinary fenced source in a viewer without Mermaid rendering; math, task lists and tables can also differ. This fixture lets you observe those differences directly.

Markups runs core editing in your browser. If you use optional AI Writer, selected content may be sent to your configured provider. See the privacy policy for data-handling details.

Continue with focused examples

Use the Mermaid diagram examples, KaTeX math examples and Markdown-to-PDF walkthrough for a deeper look at each capability.