Free Markdown to HTML API Endpoint

Call the free Markdown to HTML API endpoint

Post the Markdown under a data key:

curl -X POST https://aisenseapi.com/services/v1/markdown_to_html \
  -H "Content-Type: application/json" \
  -d '{"data": "# Report\n\n- **3** jobs done\n- [ ] one left\n\n| Job | Time |\n|---|--:|\n| sync | 2.1 s |"}'

{"html":"<h1>Report</h1>\n<ul>\n<li><strong>3</strong> jobs done</li>\n<li><input type=\"checkbox\" disabled=\"\" /> one left</li>\n</ul>\n<table>\n<thead>\n<tr>\n<th>Job</th>\n<th style=\"text-align: right\">Time</th>\n</tr>\n</thead>\n<tbody>\n<tr>\n<td>sync</td>\n<td style=\"text-align: right\">2.1 s</td>\n</tr>\n</tbody>\n</table>"}

The html value is a fragment, with no <html> or <body> around it:

<h1>Report</h1>
<ul>
<li><strong>3</strong> jobs done</li>
<li><input type="checkbox" disabled="" /> one left</li>
</ul>
<table>
<thead>
<tr>
<th>Job</th>
<th style="text-align: right">Time</th>
</tr>
</thead>
<tbody>
<tr>
<td>sync</td>
<td style="text-align: right">2.1 s</td>
</tr>
</tbody>
</table>

To go the other way, use the HTML to Markdown API endpoint.

Safe to show

The HTML can go into a page as it is, even when the Markdown came from someone else. Raw HTML in the Markdown is shown as text, never passed through, and a link or image whose scheme is not on a short list is shown as its text:

curl -X POST https://aisenseapi.com/services/v1/markdown_to_html \
  -H "Content-Type: application/json" \
  -d '{"data": "<script>alert(1)</script> and [click](javascript:alert(1))"}'

{"html":"<p>&lt;script&gt;alert(1)&lt;/script&gt; and click</p>"}

Anything else, javascript:, vbscript:, data:text/html and SVG data included, however it is spelled or escaped, becomes text. Attribute values are escaped, so a title or URL cannot add an attribute of its own.

What it reads

Markdown to PDF in one pipe

The HTML to PDF API endpoint takes the html as its data and stores the PDF for 24 hours:

curl -s -X POST https://aisenseapi.com/services/v1/markdown_to_html \
  -H "Content-Type: text/markdown" --data-binary @report.md \
  | jq '{data: .html}' \
  | curl -s -X POST https://aisenseapi.com/services/v1/html2pdf \
      -H "Content-Type: application/json" --data-binary @-

The answer carries the storage_url of the PDF.

Sending the input

Send the text as {"data": "..."} with Content-Type: application/json, or as the raw request body with any other content type, such as text/markdown. It has to be UTF-8.

Windows and old Mac line ends are read as line ends.

Errors

Each refusal also carries fix, a sentence saying what to send instead.

Common uses

Privacy and limits

The base URL is https://aisenseapi.com/services/v1. There is no key, no account and no sign-up step. One request carries at most 256 KiB of Markdown and 20000 lines. The service-wide limit is 5000 requests per IP address per day. Every endpoint in the collection is listed on the Free public REST APIs reference.

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