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eta (η)

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You’re viewing the source for Eta v3, which we just released! For v2, visit the old branch.


Eta is a lightweight and blazing fast embedded JS templating engine that works inside Node, Deno, and the browser. It’s written in TypeScript and emphasizes great performance, configurability, and small bundle size.

🌟 Features

  • 📦 0 dependencies
  • 💡 Only ~3.5 KB minzipped
  • ⚡️ Written in TypeScript
  • ✨ Deno support (+ Node and browser)
  • 🚀 Super Fast
  • 🔧 Configurable
    • Plugins, custom delimiters, caching
  • 🔨 Powerful
    • Precompilation, partials, async
    • Layout support!
  • 🔥 Reliable
    • Better quotes/comments support
      • ex. <%= someval + "string %>" %> compiles correctly, while it fails with doT or EJS
    • Great error reporting
  • ⚡️ Exports ES Modules as well as UMD
  • 📝 Easy template syntax

Get Started

For more thorough documentation, visit

Install Eta

npm install eta

In the root of your project, create templates/simple.eta

Hi <%= %>!

Then, in your JS file:

import { Eta } from "eta";
// import { Eta } from "";

const eta = new Eta({ views: path.join(__dirname, "templates") });

// Render a template

const res = eta.render("./simple", { name: "Ben" });
console.log(res); // Hi Ben!


Where did Eta’s name come from?

“Eta” means tiny in Esperanto. Plus, it can be used as an acronym for all sorts of cool phrases: “ECMAScript Template Awesomeness”, “Embedded Templating Alternative”, etc….

Additionally, Eta is a letter of the Greek alphabet (it stands for all sorts of cool things in various mathematical fields, including efficiency) and is three letters long (perfect for a file extension).


Visual Studio Code

@shadowtime2000 created eta-vscode.


eslint-plugin-eta was created to provide an ESLint processor so you can lint your Eta templates.


Currently there is no official Webpack integration but @clshortfuse shared the loader he uses:

  loader: 'html-loader',
  options: {
    preprocessor(content, loaderContext) {
      return eta.render(content, {}, { filename: loaderContext.resourcePath });

To operate with Eta templates in Node-RED: @ralphwetzel/node-red-contrib-eta


Projects using eta

  • Docusaurus v2: open-source documentation framework that uses Eta to generate a SSR build
  • swagger-typescript-api: Open source typescript api codegenerator from Swagger. Uses Eta as codegenerator by templates
  • html-bundler-webpack-plugin: Webpack plugin make easily to bundle HTML pages from templates, source styles and scripts
  • SmartDeno: SmartDeno is an easy to setup web template using Deno & Oak
  • Add yours!


Made with ❤ by @nebrelbug and all these wonderful contributors (emoji key):

Ben Gubler
Ben Gubler

💻 💬 📖 ⚠️
Clite Tailor
Clite Tailor

🤔 💻

💻 🤔
Craig Morten
Craig Morten

Rajan Tiwari
Rajan Tiwari


💻 🤔 ⚠️
Hamza Hamidi
Hamza Hamidi

Calum Knott
Calum Knott




This project follows the all-contributors specification. Contributions of any kind are welcome!


  • Async support, file handling, and error formatting were based on code from EJS, which is licensed under the Apache-2.0 license. Code was modified and refactored to some extent.
  • Syntax and some parts of compilation are heavily based off EJS, Nunjucks, and doT.