Fallow documentation

Fallow is codebase intelligence for TypeScript and JavaScript.

Use the static layer to find unused code, duplication, complexity hotspots, architecture drift, design-system styling drift, and feature-flag branches across your module graph. Add the optional runtime layer when you want to know what actually executed in production.

Start here

1
Run Fallow without installing
```
npx fallow
```
No config needed for the first run.
Read the results
Dead code, duplication, complexity, and styling, in one pass.

Go deeper

npx fallow dead-code
npx fallow dupes
npx fallow health
npx fallow fix --dry-run

What Fallow helps you do

Delete cold code

Remove unused files, exports, and dependencies with confidence.

Reduce duplication

Find repeated logic before it spreads.

Prioritize refactors

Use complexity and health analysis to focus cleanup work.

Add TypeScript evidence

Confirm exact symbol use, class contracts, affected files, and targeted tests.

Add runtime evidence

See hot paths, cold paths, and runtime-backed deletion evidence.

Pick your workflow

CLI

Best place to start. Works locally, in CI, and in agent loops.

VS Code

Real-time diagnostics, Code Lens, and one-click fixes in the editor.

MCP and agents

Structured tool calling for Claude Code, Cursor, and other agents.

Understand the two layers

Static analysis answers: what is connected to what?

Runtime intelligence answers: what actually ran?

They meet in fallow health.

Static vs runtime intelligence

Read the mental model before you set up runtime collection.

Most-used pages