Marked.js - github
<!doctype html>
<html>
<head>
<meta charset="utf-8"/>
<title>Marked in the browser</title>
</head>
<body>
<div id="content"></div>
<script src="https://cdn.jsdelivr.net/npm/marked/marked.min.js"></script>
<script>
document.getElementById('content').innerHTML =
marked('# Marked in the browser\n\nRendered by **marked**.');
</script>
</body>
</html>