Quick start

Get your first list of unused code, duplication, and complexity hotspots in under a minute. Then add fallow to VS Code, CI, MCP, or Fallow Cloud.

In under a minute, you get a list of unused code, duplication, and complexity hotspots in your project. Everyone starts with the same command. At the end, pick the integration that fits your work.

1. Run fallow

From your project root, run:

npx fallow

This command runs three analyses in one pass:

Dead code: unused files, exports, dependencies, cycles, boundaries, and more
Duplication: repeated logic across files
Health: complexity hotspots and refactor targets

Built-in plugins cover Next.js, Vite, Ember, Wuchale, Jest, Tailwind, PandaCSS, Contentlayer, tap, tsd, and more. The first run needs no configuration.

2. Run the focused commands you'll use most

npx fallow dead-code          # Cleanup candidates
npx fallow dupes              # Repeated logic
npx fallow health             # Complexity and refactor targets
npx fallow review             # Advisory review brief over changed files (always exits 0)
npx fallow fix --dry-run      # Preview automatic cleanup

dead-code reports unused files, exports, types, dependencies, circular dependencies, and boundary violations. See the dead code guide.
dupes finds AST-based duplicates in the default mild mode. To also find clones with renamed variables, add --mode semantic. See the duplication guide.
health reports complexity findings, maintainability per file, hotspots, and ranked refactor targets. See the health explanation.
fix --dry-run shows the automatic cleanup without changing files. To apply it, remove --dry-run. See the auto-fix guide.

To clean up or refactor TypeScript, add --type-aware when aliases, re-exports, class contracts, packages, or exact consumers affect the decision. This optional semantic pass is slower. See Type-aware TypeScript analysis.

3. Pick your next step

Does your existing repo have a backlog of findings? Follow Adopt Fallow in an existing repo for a step-by-step cleanup. Then come back here to set up CI or VS Code.

Use it in VS Code

Get real-time diagnostics, Code Lens above exports, and one-click fixes.

Use it in CI

Use fallow as a PR and merge gate, with SARIF or MR annotations.

Use it from agents

Add MCP to give Claude Code, Cursor, and other agents structured tool calls.

Add runtime evidence

Add production execution data to fallow health.

Optional: create a config

Fallow works without a config file. To customize it, run:

fallow init

fallow init detects your project structure and writes a config for it. It also adds .fallow/ to your .gitignore.

{
  "$schema": "https://raw.githubusercontent.com/fallow-rs/fallow/main/schema.json",
  "entry": ["src/workers/*.ts", "scripts/*.ts"],
  "ignorePatterns": ["**/*.generated.ts"],
  "rules": {
    "unused-files": "error",
    "unused-exports": "warn",
    "unused-types": "off"
  }
}

To migrate from knip or jscpd, run fallow migrate, or read the knip or jscpd guide.

Optional: Fallow Cloud

The static layer of fallow is free and open source (MIT). To learn which code actually executed in production, add Fallow Cloud, the paid product. A single local capture is free. The trial below turns on continuous and multi-capture monitoring for 30 days:

npx fallow license activate --trial --email you@company.com
npx fallow coverage setup
npx fallow health --runtime-coverage ./coverage

Before you start, read Static analysis vs production data to learn how the two layers differ. Then follow the runtime coverage guide for the setup.

1. Run fallow

2. Run the focused commands you'll use most

3. Pick your next step

Optional: create a config

Optional: Fallow Cloud

See also