uncss

Find and remove unused CSS classes across a project.

Install

./build.sh

Requires Odin in PATH.

uncss [all] [flags]

Report mode (default) — prints unused classes, no files modified:

uncss
uncss --json

Apply mode — rewrites CSS files, backups written as .bak:

uncss all
uncss all --no-backup --yes

Flag	Default	Description
`--ext=<list>`	`.css,.less,.scss,.sass`	CSS file extensions
`--markup-ext=<list>`	`.html,.htm,.jsx,.tsx,.vue,.svelte,.astro,.php,.erb,.hbs,.mustache,.twig,.ejs`	Markup file extensions
`--ignore=<list>`	`node_modules,dist,build,.git,.next,vendor,target`	Directory names to skip
`--no-backup`	—	Skip `.bak` backup in apply mode
`--json`	—	Machine-readable JSON output
`--yes`, `-y`	—	Skip confirmation prompt
`-h`, `--help`	—	Show help

path/to/file.css:12:1  .unused-class
path/to/other.css:34:5 .another-class

3 unused class(es) across 2 file(s)

Walk project from CWD, collect .css/.less/.scss/.sass and markup files.
Scan markup for class= / className= attribute values — build a "used classes" set.
Parse CSS: tokenize selector lists, extract .classname tokens with positions.
Diff: classes in CSS not found in markup = unused.
Report or remove.

Files containing @tailwind or @apply are skipped (Tailwind generates classes dynamically).
Rules containing &, #{, @include, @mixin, @extend are skipped (SCSS/LESS risk).
Only pure class selectors (e.g. .foo, .foo .bar, .foo:hover) are removed; selectors with tag names, IDs, or attribute selectors are kept.
Apply mode writes .bak backups by default.

Dynamic classes (`btn-${variant}`) → false positives (class appears unused but isn't).
SCSS/LESS variables and mixins not resolved.
CSS Modules hash names not supported.
CSS-in-JS (styled-components, emotion) not scanned.