Skip to content
/ bro Public
generated from openpeeps/pistachio

Bro - A super fast stylesheet language for cool kids! Alternative to SassC, DartSass SassJS and Less.


Notifications You must be signed in to change notification settings


Folders and files

Last commit message
Last commit date

Latest commit


Repository files navigation

Bro aka NimSass
πŸ˜‹ Bro ⚑ A super fast stylesheet language for cool kids!
πŸ‘‘ Written in Nim language

API reference | Download (not yet)
Github Actions Github Actions

😍 Key Features

  • ⚑ Extremely fast & Highly optimized Jump to Benchmarks
  • πŸƒ Lightweight, 1.5MB tiny executable
  • 🐱 Dependency Free / No Virtual Machine
  • πŸ’ͺ Strongly Typed = Perfect Cascading Style Sheets 🀩
  • 🌍 Works on Linux, macOS, Windows
  • πŸ”– A beautiful, improved SASS-like Syntax Learn Bro in 5 minutes
  • πŸ“š Standard Library (strings, arrays, objects, math, regex, os) Check the manual
  • πŸ‘‹ Human readable Syntax => Developer friendly
    • var & const
    • [] Arrays
    • {} Objects
    • if & case Conditionals
    • for Loop Statements
    • fn Functions & mix Mixins
      • Overloading + Closures + Forward declaration
    • CSS to BASS AST with include some.css
    • BASS imports using import std/[strings, math]
    • JSON/YAML stream to BASS using json("some.json"), yaml("some.yml")
  • πŸ‘ Built-in CSS Optimization (Autoprefixer, Minifier, CSS Alphabetize & Deduplication)
  • πŸ—Ί CSS SourceMap Generator
  • πŸ”„ CSS Reload & Browser sync Setup info
  • 🌴 Abstract Syntax Tree binary serialization
  • πŸŽ‰ Built-in HTML, JSON Documentation Generator
  • πŸ”₯ Works with Node.js & Bun.js via NAPI
  • πŸŽ† Works in Browser via WASM (unstable)
  • 🌍 Dynamically Linked Library
  • πŸ‘‰ Warnings => Unused Variables
  • πŸ‘‰ Warnings => Unused Mixins, Functions, Empty selectors
  • πŸ‘‰ Errors => invalid properties/values or typos!
  • 🏳 Recommended Extension .bass
  • 🎩 Open Source | LGPLv3 license
  • πŸ‘‘ Written in Nim language
  • πŸ˜‹ Made for Cool Kids


Bro is still under development. Expect bugs and incomplete features.


Since Bro is written in native code, anti-virus software can sometimes incorrectly flag it as a virus


Install Bro as a standalone CLI application. Get it from Releases or build it from source using Nim & Nimble.

Bro πŸ’› Nim

Integrate Bro in your Nim application

import bro

let stylesheet = """
$colors = [blue, yellow, orchid]
for $color in $colors:
    background: $color 

  p: Parser = parseStylesheet(stylesheet)
  c: Compiler = newCompiler(p.getStylesheet, minify = true)
echo c.getCSS # .bg-blue{background:blue}.bg-yellow{...

Bro πŸ’– Bun & Node.js

Integrate the most powerful CSS pre-processor in your Node.js/Bun app. Bro is available as a native addon module

let stylesheet = `
$colors = [blue, yellow, orchid]
for $color in $colors:
    background: $color
const bro = require("bro.node")
bro.compile(stylesheet) // .bg-blue{background:blue}.bg-yellow{...

Bro in Browser via Wasm

Build complex real-time web-apps using Bro + WebAssembly

<style type="text/bro" id="stylesheet">
$colors = [blue, yellow, orchid]
for $color in $colors:
    background: $color
<script src="/bro.min.js"></script>
bro.compile('#stylesheet') // .bg-blue{background:blue}.bg-yellow{...


DartSass, SassC, Bro, BroJS (via NAPI w/ Node & Bun), Sass (JS w/ Node & Bun)

1.572.876 lines of

  background: yellow
Benchmark 1: ./dart sass.snapshot test.sass:test.css --no-source-map --style=compressed
  Time (abs ≑):         4.925 s               [User: 6.060 s, System: 0.263 s]
Benchmark 2: bro test.sass test.css --min
  Time (abs ≑):        441.7 ms               [User: 422.3 ms, System: 19.9 ms]
Benchmark 3: sassc test.sass test.css --style=compressed
  Time (abs ≑):         5.757 s               [User: 5.346 s, System: 0.400 s]
Benchmark 4: bun bro.js
  Time (abs ≑):        679.0 ms               [User: 616.0 ms, System: 24.0 ms]
Benchmark 5: node bro.js
  Time (abs ≑):        653.7 ms               [User: 625.8 ms, System: 32.3 ms]
Benchmark 6: node sass.js
  Time (abs ≑):        12.783 s               [User: 19.640 s, System: 1.185 s]
Benchmark 7: bun sass.js
  Time (abs ≑):        10.485 s               [User: 20.422 s, System: 1.030 s]
  'bro test.sass test.css --min' ran
    1.48 times faster than 'node bro.js'
    1.54 times faster than 'bun bro.js'
   11.15 times faster than './dart sass.snapshot test.sass:test.css --no-source-map --style=compressed'
   13.03 times faster than 'sassc test.sass test.css --style=compressed'
   23.74 times faster than 'bun sass.js'
   28.94 times faster than 'node sass.js'

Check Benchmarks page for more numbers

Benchmarks made with [hyperfine]( on
**Ubuntu 22.04 LTS** / Ryzen 5 5600g 3.9GHz Γ— 12 / RAM 32 GB 3200MHz / SSD M.2


  • The Interpreter (Tokens, Lexer, Parser, AST, Compiler)
  • CSS Selectors ref
    • Type Selectors ref
    • Universal Selectors ref
    • Attribute Selectors ref
    • Class Selectors ref
    • ID Selectors ref
    • Pseudo-classes ref
    • Pseudo-elements ref
    • Groups of Selectors ref
    • Combinators ref
  • Compile-time
    • Variables
    • Arrays/Objects
      • Anonymous arrays and objects
    • Constants
    • Functions
      • Closures
      • Overloading
      • Recursive calls
    • Mixins
    • Conditionals (if, elif, else, and case)
    • For/Loop statements for $x in $y
    • Typed CSS properties/values
    • Warnings unused variables, functions
    • CSS Variable Declaration using var instead of --
    • String/Variable concatenation using & and backticks
  • Handle single/multi line comments
  • Memoization
  • Import CSS/BASS files
    • Implement AST caching system
  • Command Line Interface
    • CLI watch for live changes
    • CLI build BASS code to CSS
    • CLI generate source map
    • CLI ast command for generating binary AST
  • Build
    • Cross-platform compilation
    • Node.js/Bun.js via NAPI
    • Browser with WASM via Emscripten


  • Convert boring SASS to BASS
  • CLI doc command for generating documentation website

❀ Contributions & Support

🎩 License

Bro Language LGPLv3 license.Made by Humans from OpenPeeps.
Copyright Β© 2024 OpenPeeps & Contributors β€” All rights reserved.