Fallow

Codebase intelligence for TypeScript and JavaScript. Health, complexity, duplication, architecture, styling, and unused code, from one graph of your repository. One Rust binary. It needs no TypeScript compiler and no configuration to start.

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Run it in the root of any JS or TS project:

npx fallow

A pull request gate on a fictional storefront monorepo might look like this:

$ npx fallow audit --base HEAD~15
Audit scope: 73 changed files vs HEAD~15

● Circular dependencies (24)
  packages/storefront/src/orders/process.ts (6 cycles)
    → payment.ts → context.ts → process.ts

── Duplication ────────────────────────────────────
⚠ 185 lines (0.2%) duplicated across 6 files

● High complexity functions (28)
  packages/storefront/src/orders/payment.ts
    :566 processPayment CRITICAL
          32 ! cyclomatic   47 ! cognitive  203 lines

── Styling ────────────────────────────────────────
  font sizes mix 3 units (3 px, 2 rem, 1 em; candidate, standardize unless intentional)

✗ dead code: 68 issues · complexity: 28 findings · duplication: 7 clone groups · 73 changed files
  audit gate excluded 98 inherited findings (run with --gate all to enforce)

Illustrative output for a fictional project. The gate fails (exit code 1) on findings in changed files. Findings that existed before the change are excluded.

fallow builds a repository graph of modules, exports, dependencies, functions, and styling tokens. Its analyses use that graph to find complexity, architecture drift, duplication, unused code, and risks in a pull request.

fallow runs in four places. All four read the same config file and use the same analysis engine.

What fallow finds