KaTeX is a fast, easy-to-use JavaScript library for TeX math rendering on the web.
Fast: KaTeX renders its math synchronously and doesn't need to reflow the page. See how it compares to a competitor in this speed test.
Print quality: KaTeX's layout is based on Donald Knuth's TeX, the gold standard for math typesetting.
Self contained: KaTeX has no dependencies and can easily be bundled with your website resources.
Server side rendering: KaTeX produces the same output regardless of browser or environment, so you can pre-render expressions using Node.js and send them as plain HTML.
KaTeX is compatible with all major browsers, including Chrome, Safari, Firefox, Opera, and Edge.
<!DOCTYPE html><!-- KaTeX requires the use of the HTML5 doctype. Without it, KaTeX may not render properly --><html><head><linkrel="stylesheet"href="https://cdn.jsdelivr.net/npm/katex@0.16.45/dist/katex.min.css"integrity="sha384-UA8juhPf75SzzAMA/4fo3yOU7sBJ0om7SCD2GHq0fZqZco6tr1UCV7nUbk9J90JM"crossorigin="anonymous"><!-- The loading of KaTeX is deferred to speed up page rendering --><scriptdefersrc="https://cdn.jsdelivr.net/npm/katex@0.16.45/dist/katex.min.js"integrity="sha384-Tt7wBxLKwSzFVRET4O4U9H6v8MNaQ/CjN2FMP4xFm0ErrFu6aNqoonRVW5W40iGI"crossorigin="anonymous"></script><!-- To automatically render math in text elements, include the auto-render extension: --><scriptdefersrc="https://cdn.jsdelivr.net/npm/katex@0.16.45/dist/contrib/auto-render.min.js"integrity="sha384-bjyGPfbij8/NDKJhSGZNP/khQVgtHUE5exjm4Ydllo42FwIgYsdLO2lXGmRBf5Mz"crossorigin="anonymous"onload="renderMathInElement(document.body);"></script></head>
...
</html>
Call katex.renderToString to generate an HTML string of the rendered math,
e.g., for server-side rendering. For example:
var html = katex.renderToString("c = \\pm\\sqrt{a^2 + b^2}", {
throwOnError: false
});
// '<span class="katex">...</span>'
Make sure to include the CSS and font files in both cases.
If you are doing all rendering on the server, there is no need to include the
JavaScript on the client.
The examples above use the throwOnError: false option, which renders invalid
inputs as the TeX source code in red (by default), with the error message as
hover text. For other available options, see the
API documentation,
options documentation, and
handling errors documentation.
MathJax is another popular JavaScript library for displaying mathematical notation in web pages. It supports a wider range of input formats, including TeX, MathML, and AsciiMath. MathJax is known for its high-quality rendering and extensive configurability, but it is generally slower than KaTeX.
AsciiMath is a simpler alternative to KaTeX and MathJax, designed for ease of use. It uses a more human-readable syntax compared to TeX. While it is easier to write and understand, it does not support as many advanced mathematical features as KaTeX or MathJax.
FAQs
Fast math typesetting for the web.
The npm package katex receives a total of 8,944,467 weekly downloads. As such, katex popularity was classified as popular.
We found that katex demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago.It has 7 open source maintainers collaborating on the project.
Package last updated on 05 Apr 2026
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