Fallow is a static analysis tool for TypeScript and JavaScript that identifies unused code, circular dependencies, code duplication, complexity hotspots, architecture boundary violations, and design-system styling drift.
The tool solves the problem of safely removing code by building a complete dependency graph of a repository—spanning imports, exports, and styling tokens—and reporting what that graph reveals about actual usage. Rather than relying on heuristics or requiring a TypeScript compiler or Node.js runtime, it performs deterministic static analysis that produces identical results across runs with stable fingerprints. An optional paid runtime layer called Fallow Runtime adds production execution evidence to identify hot paths and cold paths based on real traffic.
Fallow suits teams working with TypeScript or JavaScript codebases who need confidence that code removal is safe and want to enforce architectural boundaries and design-system consistency. The tool outputs findings in both human-readable and typed JSON formats, making it suitable for integration into CI/CD pipelines and editor workflows. It ships as an npm package alongside editor and agent integrations that resolve the project-local binary, and can also be installed via pnpm, yarn, or cargo.
The project maintains a continuous integration pipeline with coverage tracking and performance benchmarking. Runs are deterministic with stable fingerprints, allowing developers to re-run analysis to verify that edits are safe. The tool provides an LSP server and MCP integration for editor support, and includes a Docker Compose example for containerized deployment.
