# parcel-bundler/lightningcss

An extremely fast CSS parser, transformer, bundler, and minifier written in Rust.

Repository: https://github.com/parcel-bundler/lightningcss
Canonical: https://ross.abutalabs.com/products/lightningcss
Homepage: https://lightningcss.dev
Language: Rust
License: MPL-2.0
License Family: copyleft
Topics: css, parser, compiler, minifier, rust, build-tool
Last push: 2026-08-09T06:01:32+00:00

## Health v2 (maintenance only)
Score: 92/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 96, release rhythm 81, longevity 100
- inputs: {"age_days": 1789, "days_push": 24, "days_rel": 44, "gap_med": 53, "n_releases_24m": 12}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 7665, forks 297 (observed 2026-08-28T04:10:02.271379+00:00)

## What it is
Lightning CSS is an extremely fast CSS parser, transformer, bundler, and minifier written in Rust, usable as a Rust or JavaScript library, a standalone CLI, or built into tools like Parcel, webpack, and Vite. It provides typed property values, browser-target-based vendor prefixing, syntax lowering for modern CSS features, CSS modules support, and highly optimized minification.

## Use cases
- minify css to reduce bundle size
- add and remove vendor prefixes based on browser targets
- transpile modern css nesting to compatible syntax
- bundle css files with @import inlining
- parse css into a typed ast from rust or node
- scope class names with css modules
- replace autoprefixer and postcss-preset-env in a build pipeline
- convert modern color functions like oklab to fallback formats

## When to choose
- you need dramatically faster css processing than javascript-based tools like cssnano
- you want smaller minified css output
- you need to support modern css syntax while targeting older browsers
- you want a single tool replacing autoprefixer, postcss-preset-env, and css modules handling
- you are building a rust or node toolchain that needs a css parser

## When to avoid
- you rely on custom postcss plugins like tailwindcss that lightningcss cannot replace
- you need a pure javascript implementation without native binaries or wasm
- your project depends on postcss plugin ecosystem extensibility

## Facets
- artifact type: library
- maturity: active
- function: parser, compiler, build-tool, css-framework
- domain: web-development, frontend, developer-tools, performance
- platform: cross-platform, rust, cli, wasm
- tags: css, minifier, css-transformer, css-modules, vendor-prefixing, browserslist, syntax-lowering, bundler, nodejs, web-server

## Member repositories
- parcel-bundler/lightningcss (main) score 92

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:10:02.271379+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T17:36:04.898752+00:00, confidence not recorded.
  - readme: https://github.com/parcel-bundler/lightningcss (fetched 2026-08-28T04:10:02.271379+00:00, sha 276c54dd0ee4)
  - homepage: https://lightningcss.dev (fetched 2026-08-29T08:31:49.091418+00:00, sha 7aa1927af2fa)
  - site_page: https://lightningcss.dev/docs.html (fetched 2026-08-29T08:31:49.100702+00:00, sha 6ca35fa24ea1)
  - registry_crates: https://crates.io/api/v1/crates/lightningcss (fetched 2026-08-29T08:31:49.104755+00:00, sha e0dc196038b6)
  - site_page: https://lightningcss.dev/css-modules.html (fetched 2026-08-29T08:31:49.102857+00:00, sha c2e70a33419b)
- Data as of 2026-08-30T08:39:29.467469+00:00.