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KaTeX is a fast, easy-to-use JavaScript library for TeX math rendering on the web.

KaTeX supports all major browsers, including Chrome, Safari, Firefox, Opera, Edge, and IE 9 - IE 11. More information can be found on the list of supported commands and on the wiki.


You can download KaTeX and host it on your server or include the katex.min.js and katex.min.css files on your page directly from a CDN:

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.9.0-beta1/katex.min.css" integrity="sha384-VEnyslhHLHiYPca9KFkBB3CMeslnM9CzwjxsEbZTeA21JBm7tdLwKoZmCt3cZTYD" crossorigin="anonymous">
<script src="https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.9.0-beta1/katex.min.js" integrity="sha384-O4hpKqcplNCe+jLuBVEXC10Rn1QEqAmX98lKAIFBEDxZI0a+6Z2w2n8AEtQbR4CD" crossorigin="anonymous"></script>

In-browser rendering

Call katex.render with a TeX expression and a DOM element to render into:

katex.render("c = \\pm\\sqrt{a^2 + b^2}", element);

If KaTeX can’t parse the expression, it throws a katex.ParseError error.

Server side rendering or rendering to a string

To generate HTML on the server or to generate an HTML string of the rendered math, you can use katex.renderToString:

var html = katex.renderToString("c = \\pm\\sqrt{a^2 + b^2}");
// '<span class="katex">...</span>'

Make sure to include the CSS and font files, but there is no need to include the JavaScript. Like render, renderToString throws if it can’t parse the expression.


Any HTML generated by KaTeX should be safe from <script> or other code injection attacks. (See maxSize below for preventing large width/height visual affronts.) Of course, it is always a good idea to sanitize the HTML, though you will need a rather generous whitelist (including some of SVG and MathML) to support all of KaTeX.

Handling errors

If KaTeX encounters an error (invalid or unsupported LaTeX), then it will throw an exception of type katex.ParseError. The message in this error includes some of the LaTeX source code, so needs to be escaped if you want to render it to HTML. In particular, you should convert &, <, > characters to &amp;, &lt;, &gt; (e.g., using _.escape) before including either LaTeX source code or exception messages in your HTML/DOM. (Failure to escape in this way makes a <script> injection attack possible if your LaTeX source is untrusted.)

Rendering options

You can provide an object of options as the last argument to katex.render and katex.renderToString. Available options are:

For example:

katex.render("c = \\pm\\sqrt{a^2 + b^2}\\in\\RR", element, {
  displayMode: true,
  macros: {
    "\\RR": "\\mathbb{R}"

Automatic rendering of math on a page

Math on the page can be automatically rendered using the auto-render extension. See the Auto-render README for more information.

Font size and lengths

By default, KaTeX math is rendered in a 1.21× larger font than the surrounding context, which makes super- and subscripts easier to read. You can control this using CSS, for example:

.katex { font-size: 1.1em; }

KaTeX supports all TeX units, including absolute units like cm and in. Absolute units are currently scaled relative to the default TeX font size of 10pt, so that \kern1cm produces the same results as \kern2.845275em. As a result, relative and absolute units are both uniformly scaled relative to LaTeX with a 10pt font; for example, the rectangle \rule{1cm}{1em} has the same aspect ratio in KaTeX as in LaTeX. However, because most browsers default to a larger font size, this typically means that a 1cm kern in KaTeX will appear larger than 1cm in browser units.

Common Issues







KaTeX is licensed under the MIT License.