fallow: codebase intelligence for TypeScript and JavaScript

Production mode restricts analysis to code that ships to users, ignoring test and development files.

fallow dead-code --production

Or set it in your config:

// .fallowrc.json
{
  "production": true
}

What changes in production mode

Behavior	Default	Production
Test files (`.test.`, `.spec.`, `__tests__/`)	Included	Excluded
Story files (`.stories.`)	Included	Excluded
Mock files (`__mocks__/`)	Included	Excluded
Package.json scripts analyzed	All	Only `start`, `build`, `serve`, `preview`, `prepare`, `prepublishOnly`, `postinstall`, and `pre`/`post` lifecycle hooks for `start`, `build`, `serve`, `install`
Unused devDependencies	Reported	Skipped
Type-only dependencies	Not flagged	Flagged (should be devDependencies)

$ fallow dead-code --production

● Unused exports (2)
  src/utils/format.ts
    :12 formatCurrency
    :28 formatPercentage
  Exported symbols with zero references: https://docs.fallow.tools/explanations/dead-code#unused-exports

● Unused dependencies (1)
  moment
  Packages in dependencies never imported: https://docs.fallow.tools/explanations/dead-code#unused-dependencies

● Type-only dependencies (1)
  zod  →  move to devDependencies (only imported via 'import type')
  Production dependencies only used as types: https://docs.fallow.tools/explanations/dead-code#type-only-dependencies

✗ 4 issues (19ms, production mode, 623/847 files)

Type-only dependency detection

In production mode, fallow detects dependencies that are only imported via import type:

import type { Config } from 'some-package';  // Type-only, erased at runtime

These packages belong in devDependencies since types are erased at runtime and don’t need to be installed in production.

In monorepos, production mode catches dependencies that should be devDependencies, keeping each package’s install footprint minimal.

Per-analysis production mode

Combined mode (bare fallow) and fallow audit can enable production mode per analysis instead of globally:

// .fallowrc.json
{
  "production": {
    "health": true,
    "deadCode": false,
    "dupes": false
  }
}

Use --production-health, --production-dead-code, or --production-dupes for one invocation, or FALLOW_PRODUCTION_HEALTH=true and the related env vars in CI. The global --production flag still enables production mode for every analysis. Precedence (highest to lowest): CLI flags, per-analysis env var, global FALLOW_PRODUCTION, config. CLI flags only enable; env vars and config can also disable. Worked examples:

# Run health in production mode, dead-code and dupes on the full tree
fallow --production-health

# Same, via env var (useful in CI templates that pass env-only)
FALLOW_PRODUCTION_HEALTH=true fallow

# Per-analysis env wins over the global env, so this runs health in production
# mode even though the global env says off (the typical CI-template case)
FALLOW_PRODUCTION=false FALLOW_PRODUCTION_HEALTH=true fallow

# CLI flags beat env vars; this enables all three regardless of FALLOW_PRODUCTION_* env
fallow --production

CI Integration

Use production mode in your CI pipeline for lean, fast checks.

Rules & Severity

Control which issue types are errors, warnings, or disabled.

Getting Started

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Explanations

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Production mode

What changes in production mode

Type-only dependency detection

Per-analysis production mode

See also

CI Integration

Rules & Severity

​What changes in production mode

​Type-only dependency detection

​Per-analysis production mode

​See also

CI Integration

Rules & Severity

What changes in production mode

Type-only dependency detection

Per-analysis production mode

See also