Render markdown API

Convert markdown into safe, sanitised HTML.

POST /api/v1/render is the Markdown Viewer API endpoint for converting markdown to HTML. Output is sanitised, supports GitHub Flavored Markdown (tables, task lists, strikethrough), and returns a deterministic { data: { html, characters } } response.

Overview

Renders a markdown document into HTML. Output is sanitised with DOMPurify — script tags, inline event handlers, and `javascript:` URLs are removed. Supports CommonMark plus GitHub Flavored Markdown (tables, task lists, strikethrough, autolinks, fenced code).

Request

Authenticate with Authorization: Bearer YOUR_API_KEY and send a JSON body containing the parameters below. Pick your language:

curl -X POST 'https://trymarkdownviewer.com/api/v1/render' \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"markdown":"# Hello world\n\nWelcome to **Markdown Viewer**."}'

Body parameters

Field	Type	Required	Description
markdown	string	required	Markdown source. Max 256 KiB.
sanitize	boolean	optional	Reserved. Output is always sanitised today.

Response

Success responses are wrapped in a data field. Errors use { error: { code, message } } with an appropriate HTTP status — see the error reference.

{
  "data": {
    "html": "<h1 id=\"hello-world\">Hello world</h1>\n<p>Welcome to <strong>Markdown Viewer</strong>.</p>",
    "characters": 78
  }
}

Use cases

User-generated content

Render comments, posts, and wiki pages safely. DOMPurify strips XSS payloads before the HTML leaves our server.

LLM / AI output

Display markdown responses from ChatGPT, Claude, or Gemini in your product without writing your own parser.

Documentation pipelines

Render docs at build time or on-demand. Same engine as the editor — no surprises between preview and production.

Email / report rendering

Convert markdown templates to HTML for transactional emails, dashboards, or PDF generation upstream.

Production tips

Cache responses by content hash — identical markdown always renders to identical HTML.
Heading ids are auto-generated and slug-safe — use them as anchors for an in-page TOC.
Inline HTML in the input is allowed but heavily restricted by the sanitizer allowlist.

Render markdown FAQ

Is the HTML output safe to inject into the DOM?

Yes. Every response is sanitised with DOMPurify using a conservative allowlist — script tags, inline event handlers (onclick, onerror), javascript: URLs, and unsafe iframes are stripped before the response leaves our server.

Which markdown flavour does /api/v1/render support?

CommonMark plus GitHub Flavored Markdown: tables, task lists, strikethrough, autolinks, fenced code blocks. Footnotes and math are not currently supported via the API; if you need them, our editor renders them client-side.

What's the maximum markdown size?

256 KiB per request. If your document is larger, split it into chunks (eg. by heading or section) and render each piece separately — the renderer is deterministic, so the result is stable.

Does the renderer add CSS or assume a stylesheet?

No. The response is plain semantic HTML — h1/h2/p/ul/code/etc. — style it however you want with your own CSS or Tailwind classes. Code blocks are emitted as <pre><code class="language-xyz">.

Try in browser

Free tools that run the same logic locally — no API key, no upload.

Try it

Send a real request against your account in the API playground. Errors there link straight back to the error reference.