knip-dead-code

Knip detects unused files, dependencies, exports, types, enum members, and class members in JS/TS projects per the Knip docs (opens in new window). Requires Node ≥ 20.19.0 (or Bun).

When to use

• After a feature deletion when "everything still compiles" but you suspect dead code.
• Periodic cleanup to remove unused npm dependencies (security + bundle-size win).
• Pre-merge gate to prevent new dead exports from accumulating.

Step 1 - Install

# Recommended: setup wizard (auto-detects framework)
npm init @knip/config

# Manual
npm install -D knip typescript @types/node

Add package.json script:

{
  "scripts": {
    "knip": "knip"
  }
}

Per the Knip docs (opens in new window).

Step 2 - Configure entry points

knip.json:

{
  "$schema": "https://unpkg.com/knip@5/schema.json",
  "entry": [
    "src/index.ts",
    "src/cli.ts",
    "scripts/**/*.ts"
  ],
  "project": ["src/**/*.{ts,tsx}"],
  "ignore": ["src/**/*.generated.ts"],
  "ignoreDependencies": [
    "@types/node"
  ],
  "ignoreExportsUsedInFile": true
}

Or knip.config.ts for typed config.

Entry vs project: entry = files Knip starts walking the import graph from. project = the universe of files it considers reachable. Anything in project not reached from entry is unused.

Step 3 - First run

npx knip

Exit code: 0 if clean, non-zero if unused items found. Shows:

Unused files (3)
Unused dependencies (2)
Unused exports (12)
Unused exported types (4)
Unused exported enum members (1)

Step 4 - Use framework plugins

For framework-aware scanning, enable plugins (auto-detected by npm init @knip/config):

{
  "next": {
    "entry": ["next.config.{js,ts,cjs,mjs}", "app/**/page.{js,ts,tsx}"]
  },
  "playwright": {
    "config": "playwright.config.ts",
    "entry": ["e2e/**/*.spec.ts"]
  }
}

Plugin list (Next.js, Remix, Astro, Vite, Storybook, Playwright, Jest, etc.) - see the Knip plugins page (opens in new window).

Step 5 - Limit output during cleanup

# Show only top 5 of each issue type - useful when first adopting
npx knip --max-show-issues 5

Per the Knip docs (opens in new window) for overwhelming output.

Step 6 - CI gate

# GitHub Actions
- name: Knip dead-code check
  run: npx knip

Fails build on any new dead code. For brownfield rollout, baseline existing dead code first:

# Snapshot current findings; CI only fails on additions
npx knip --no-exit-code > knip-baseline.txt

Step 7 - Per-issue triage

Anti-patterns

Limitations

• Dynamic imports with computed paths (import(\./${name}`)) cannot be statically tracked; Knip flags dependencies as unused even though they load at runtime. Use ignoreDependencies` for these cases.
• Side-effect imports (e.g., import "./polyfill") are tracked, but reflection-heavy code (DI containers that instantiate via string names) requires manual ignore entries.

References

• Knip docs (opens in new window) - install, entry/project config, framework plugins
• Knip plugins page (opens in new window) - full plugin list (Next.js, Remix, Astro, Storybook, Vite, etc.)