CoffeeScript

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Score6.8

Rank#9 of 28

Free planNo

Runs onAPI, Linux, macOS, Web, Windows

Summary

CoffeeScript is a programming language that compiles into JavaScript, producing code that runs without a CoffeeScript interpreter. JavaScript libraries can be used from CoffeeScript, and JavaScript can also use CoffeeScript libraries. Version 2 emits modern JavaScript syntax, including classes and arrow functions, and supports async functions and JSX. The coffee command can run scripts, compile .coffee files into .js files, and open an interactive REPL. It can also create external or inline source maps. CoffeeScript is installed through npm, either globally or as a project dependency, and is free and open source. The core compiler can run in a browser or another JavaScript environment; the command-line utility requires Node 6 or later. Babel transpilation is supported when @babel/core is installed. Integrations are listed for build tools such as Gulp and Webpack, editors including Vim and Visual Studio Code, and Jest testing. JSX output always needs transpilation, and users are responsible for ensuring their runtime supports the modern JavaScript features they use or transpiling the result.

Who it is for

CoffeeScript suits developers who want to write code that compiles to JavaScript and use JavaScript libraries in either direction. It may also suit users who need a command-line compiler, source maps, or an interactive REPL.

What is good

Compiles to JavaScript without a runtime interpreter
Supports async functions and JSX syntax
CLI can run scripts and provide an interactive REPL
Can generate inline or external source maps
Core compiler can run in a browser

What to know first

Command-line utility requires Node 6 or later
JSX output always requires transpilation
Babel transpilation requires @babel/core

Everything Xiaomi review

CoffeeScript: the full review

CoffeeScript offers a source language and tooling that produce JavaScript, with support for modern syntax and common development integrations. Check runtime support for the JavaScript features you use, and plan to transpile JSX output.

CoffeeScript is a language that compiles to JavaScript, aimed at developers who prefer its syntax but need to work with JavaScript libraries and environments. Its strongest case is a free, open-source source-to-source workflow with a CLI, compiler API and useful build integrations; its main caveat is that modern output still has to match your target runtime.

Overview

CoffeeScript does not add a separate runtime: it compiles source into JavaScript that runs without CoffeeScript interpretation. That keeps it compatible with existing JavaScript libraries, and JavaScript can also use libraries written in CoffeeScript. For teams adopting it incrementally, that interoperability makes it more practical than a language requiring a distinct runtime or ecosystem.

CoffeeScript 2 emits modern JavaScript, including classes and arrow functions, and supports async functions and JSX syntax. The trade-off is that syntax support does not guarantee runtime compatibility: users must ensure their JavaScript environment supports the features they use or transpile the output. JSX output always needs transpilation.

Key features

The coffee command can run scripts, compile .coffee files to JavaScript and open an interactive REPL. It can also generate inline or external source maps, useful when debugging compiled output. The Node API compiles strings and can return source maps or an abstract syntax tree, giving build systems more direct access than a CLI-only workflow.

CoffeeScript installs through npm, globally or as a project dependency. The command-line utility requires Node 6 or later; the compiler core can run in any JavaScript environment, including a browser. Babel transpilation is built in but requires @babel/core. The integrations resources cover Gulp, Webpack, Grunt and Broccoli, editors such as Atom, Emacs, Vim and Visual Studio Code, and Jest via jest-preset-coffeescript.

There are compatibility details to account for: the site says most supported modern JavaScript features run natively in Node 7.6 or later, while modules require Node 12 or later and type set to module in package.json. JSX must be transpiled. Those requirements put the burden on the project to align output, tooling and runtime.

Pricing

CoffeeScript is free and open source, with no free trial because there is no paid plan to trial. It suits individuals and teams who want to compile CoffeeScript without a software subscription. The available facts give no paid tiers or plan quotas; npm installation and Node requirements are the practical setup considerations.

Platforms

CoffeeScript is listed for API, Linux, macOS, web and Windows. Its compiler core can run in a browser or another JavaScript environment; the command-line path depends on Node.js 6 or later.

Who it's for

Choose CoffeeScript if you want its source syntax while retaining access to JavaScript libraries and build chains, or need to compile from a CLI or API. It is a weaker fit when a project cannot accommodate transpilation or careful runtime compatibility checks, especially for JSX or newer JavaScript features.

Pros and cons

Pro: Compiles to JavaScript without a runtime interpreter, while allowing use of JavaScript libraries in either direction.
Pro: CLI, API, source maps and an interactive REPL support both direct use and integration into a build workflow.
Pro: Free and open source, with resources for common build tools, editors and Jest testing.
Con: Users must check modern JavaScript feature support or transpile output; JSX always requires transpilation.
Con: The CLI requires Node 6 or later, and modules require Node 12 or later with a package setting.

Alternatives

Code Transpilers is the broader category to browse. Consider SWC for a free, open-source Rust-based developer toolchain. Transcrypt is another free, open-source option, licensed under Apache 2.0. Google Web Toolkit offers a free, open-source alternative under Apache 2.0.

Babel is a free community-funded option with no paid tiers or usage limits stated. ClojureScript is free, open source and licensed under the Eclipse Public License 1.0. Kotlin/JS is a free Kotlin compiler target for JavaScript configured with the Kotlin Multiplatform Gradle plugin. Cython is freely available under Apache 2.0. Dart pub is another option.

Verdict

CoffeeScript is a sensible choice for developers who want its language syntax without giving up JavaScript interoperability, and who can manage output compatibility in their build. Its free compiler, CLI and API make it easy to adopt without a licensing cost; look elsewhere if your project needs to avoid transpilation or runtime-specific checks.

Compared on code transpilers

Syntax-version conversion: Yescoffeescript.org
Intermediate output: Yescoffeescript.org
CLI access: Yescoffeescript.org
API access: Yescoffeescript.org
Conversion mode: source-to-sourcecoffeescript.org

Facts

Purpose: CoffeeScript is a language that compiles into JavaScript.coffeescript.org · 2 Oct 2026
Runtime: CoffeeScript compiles to equivalent JavaScript with no interpretation at runtime.coffeescript.org · 2 Oct 2026
JavaScript libraries: Existing JavaScript libraries can be used from CoffeeScript and vice versa.coffeescript.org · 2 Oct 2026
Modern output: CoffeeScript 2 produces modern JavaScript syntax, including JavaScript classes and arrow functions.coffeescript.org · 2 Oct 2026
Language features: CoffeeScript 2 includes async function and JSX syntax support.coffeescript.org · 2 Oct 2026
Command line: The coffee command can execute scripts, compile .coffee files to .js, and provide an interactive REPL.coffeescript.org · 2 Oct 2026
Source maps: The command line supports generating external or inline source maps alongside compiled JavaScript.coffeescript.org · 2 Oct 2026
Node.js: The command-line utility requires Node 6 or later, while the core compiler can run in any JavaScript environment or in a browser.coffeescript.org · 2 Oct 2026
Transpilation: CoffeeScript has built-in support for Babel transpilation, which requires @babel/core to be installed.coffeescript.org · 2 Oct 2026
Integrations: The integrations page lists Gulp, Webpack, Grunt, and Broccoli as JavaScript build-chain tools.coffeescript.org · 2 Oct 2026
Editor support: The integrations page lists CoffeeScript support for code editors including Atom, Emacs, Vim, and Visual Studio Code.coffeescript.org · 2 Oct 2026
Testing integration: The integrations page lists Jest with jest-preset-coffeescript for testing.coffeescript.org · 2 Oct 2026
Support: The maker directs bug reports, feature proposals, and ideas to its GitHub issues page and identifies a mailing list as a place to ask questions.github.com · 2 Oct 2026
Runtime compatibility: The maker notes that JSX output always requires transpilation and that modules require Node 12 or later with type set to module in package.json.coffeescript.org · 2 Oct 2026
Compatibility: CoffeeScript can use existing JavaScript libraries, and JavaScript can use CoffeeScript libraries.coffeescript.org · 3 Oct 2026
Modern JavaScript: CoffeeScript 2 compiles to modern JavaScript syntax and includes support for async functions and JSX.coffeescript.org · 3 Oct 2026
Installation: CoffeeScript is installed through npm, either globally or as a project dependency.coffeescript.org · 3 Oct 2026
Browser use: The core compiler does not depend on Node and can run in any JavaScript environment, including a browser.coffeescript.org · 3 Oct 2026
Compiler API: The Node API can compile strings of CoffeeScript and optionally generate source maps or an abstract syntax tree.coffeescript.org · 3 Oct 2026
Editor and framework support: The integrations section links to resources for build tools, code editors, frameworks, linters and formatting, and testing.coffeescript.org · 3 Oct 2026
Runtime requirements: The command-line utility requires Node 6 or later; the site says most supported modern JavaScript features run natively in Node 7.6 or later.coffeescript.org · 3 Oct 2026
Compatibility limit: JSX output always requires transpilation, and CoffeeScript says users are responsible for ensuring their runtime supports the modern features they use or transpiling the output.coffeescript.org · 3 Oct 2026
Support and community: The site links to a CoffeeScript chat and provides contribution guidance.coffeescript.org · 3 Oct 2026