Fast, safe templates for server-rendered websites.

Kiln is a template language with syntax you already know. Templates load their own data, output is escaped by default, and it runs on Node and Cloudflare Workers.

Get started

$ npm install @lucidkiln/core

Zero dependencies
Strict by default
MIT licensed

pages/product.kiln

{% set product = document("product", slug) %}

<h1>{{ product.name }}</h1>
<p>{{ product.price|formatNumber(style: "currency", currency: "GBP") }}</p>

{% island "components/stock" with { id: product.id } %}
	<p>Checking stock…</p>
{% endisland %}

How it works

Write a template. Get clean HTML.

Components take props and slots, loops know where they are, and data loads where it is used. Every example on this site is rendered by Kiln when the site builds.

page.kiln

{% set posts = documents("post", limit: 2) %}

{% for post in posts %}
	{% component "components/card" with {
		title: post.title,
		href: post.url,
		date: post.publishedAt,
	} %}
		<p>Post {{ loop.index }} of {{ loop.length }}</p>
	{% endcomponent %}
{% endfor %}

components/card.kiln

{% props title, href, date = null %}
<article class="card">
	<h2><a href="{{ href }}">{{ title }}</a></h2>
	{% if date %}
		<time>{{ date|formatDate(dateStyle: "long") }}</time>
	{% endif %}
	{% slot %}{% endslot %}
</article>

Output

<article class="card">
	<h2><a href="/blog/hello-world/">Hello, world</a></h2>
	<time>October 1, 2026</time>
	<p>Post 1 of 2</p>
</article>
<article class="card">
	<h2><a href="/blog/layouts/">Layouts in Kiln</a></h2>
	<time>October 8, 2026</time>
	<p>Post 2 of 2</p>
</article>

Why Kiln

Everything a website needs. Nothing it doesn't.

Familiar syntax

If you have used Twig, Jinja or Liquid, you can read Kiln already. Names are camelCase, like JavaScript.
Async data

Templates call async functions to load what they need. Kiln only waits where a call returns a promise, and runs calls that don't depend on each other at the same time.
Runs anywhere

No eval, no Node built-ins and no dependencies in the core. Kiln runs on Node and Cloudflare Workers.
Safe by default

Templates only read what you give them, and output is escaped. Limits stop runaway templates.
Layouts and components

Share layouts with blocks. Build components with typed props and slots. Keep small snippets in macros.
Errors that help

Every error names the template, line and column, shows the code around it and suggests a fix.

Compared

Feature	Kiln	Twig	Nunjucks	LiquidJS	Handlebars
Components with named slots	Yes	Yes	Partly: One slot	No	Partly: One slot
Props with types and defaults	Yes	Partly: Types aren't checked	No	No	No
Safe for templates you didn't write	Yes	Partly: Opt-in sandbox	No	Yes	Partly: Blocks prototypes
Async data	Yes	No	Partly: Callback API	Yes	No
Streaming	Yes	Yes	No	Partly: Node streams only	No
Server islands	Yes	No	No	No	No
Runs on Cloudflare Workers	Yes	No	Partly: Precompiled only	Yes	Partly: Precompiled only
Types generated from templates	Yes	No	No	No	No

We render the same 7 real pages with 8 JavaScript template engines, and check every engine's HTML matches before timing. Kiln precompiles templates at build time, so it stays fast on Cloudflare Workers too.

faster than Nunjucks: 5.4×
faster than LiquidJS: 62×
faster than Twing: 49×

Geometric mean across the pages, leaving out CMS data, which mostly measures waiting for data. Apple M4 Pro, Node 24.22.0.

See every result and how we measure

EngineRenders per second, higher is better

Kiln 113.4K
Pug 55.1K
Eta 50.2K
Handlebars 27.8K
Nunjucks 25.8K
EJS 20.1K
Twing 3.8K
LiquidJS 1.3K

A full article page: a layout with blocks, header and footer partials, trusted body HTML, related posts and twenty escaped comments.

Errors

Mistakes point straight at the problem.

Strict mode is on by default, so a typo is an error instead of a blank space on the page. Errors show where they happened and suggest what you meant.

Read about strict mode

KilnRenderError: Unknown variable "titel" in pages/page.kiln
at line 4, column 9. Did you mean "title"?

  3 | {% block content %}
> 4 |   <h1>{{ titel }}</h1>
    |          ^^^^^
  5 | {% endblock %}

Fire up your first page.

Install Kiln and render a page with a layout in a few minutes.

Quick start Read the docs

Fast, safe templates for server-rendered websites.

Write a template. Get clean HTML.

Everything a website needs. Nothing it doesn't.

Familiar syntax

Async data

Runs anywhere

Safe by default

Layouts and components

Errors that help

Built in, not bolted on.

Fast where it counts.

Mistakes point straight at the problem.

Fire up your first page.