jscpd

Duplicate code detector for 220+ languages — plus dead code, complexity hotspots, duplication and health trends over git history, and one health score for the whole codebase. Rust engine, self-contained binary, AI-ready with an MCP server and a token-efficient reporter.

Documentation: https://jscpd.dev

jscpd tokenizes each of its 224 supported formats the way that language defines it — its own comment and string rules, not generic text — then finds duplicated token sequences across files with a rolling Rabin-Karp hash. Opt-in passes catch copies that differ only in names or values (Type-2) or that have a few edited lines (Type-3), and an experimental one uses a code embedding model for functions that do the same thing written differently (Type-4). See How detection works for the full mechanism, and Supported formats for the full list.

Beyond duplicates, jscpd also finds dead code (--dead-code), ranks files by complexity (--complexity), tracks duplication and health over git history (--history), and rolls it all into one health score (--health) — see Features below.

Quick Start

# macOS / Linux
curl -fsSL https://jscpd.dev/install.sh | bash

# Windows (PowerShell)
irm https://jscpd.dev/install.ps1 | iex

# No install — run once with npx (Node.js)
npx jscpd .

Then scan a project:

jscpd /path/to/code

Other install methods

Method	Command	Notes
npm	npm install -g jscpd	Installs the jscpd command; prebuilt binary, no Node.js at runtime
npm (cpd command)	npm install -g cpd	Same binary, exposed as cpd
PyPI	pip install jscpd	Platform wheels with both commands; also pipx install jscpd, uv tool install jscpd, or uvx jscpd . to run without installing
Cargo	cargo install jscpd	Builds from crates.io; installs both jscpd and cpd
Homebrew	brew install jscpd	macOS / Linux
Nix	nix run github:kucherenko/jscpd -- /path/to/code	Or nix profile install github:kucherenko/jscpd
Docker	docker run --rm -v "$PWD:/src" ghcr.io/kucherenko/jscpd .	Multi-arch image built from the release binaries

GitHub Action

- uses: kucherenko/jscpd@v5
  with:
    threshold: 5

Uploads SARIF results to GitHub Code Scanning by default. See CI & Pre-Commit Hooks for all inputs and outputs.

Documentation

Document	Description
Rust engine	Installation, CLI reference, reporters, baseline, summary, complexity, dashboard, blame, config file
AI-Ready	AI reporter, agent skills, MCP server
Editors	jscpd --lsp, the language server: setup for Neovim, Helix, Sublime Text, Emacs and JetBrains IDEs
Programming API	Rust API (cpd-finder crate)
CI & Pre-Commit Hooks	GitHub Action, Docker image, pre-commit hooks
Packages	npm packages and crates that make up a release
Supported formats	All 224 formats with their file extensions
Runnable demos	One fixtures/<feature>-demo/ directory per feature, each README lists the commands with their expected output

Features

jscpd v5 is a Rust engine that ships as a self-contained binary — no runtime required — under two npm names (jscpd installs the jscpd command, cpd installs cpd), on PyPI, crates.io, Homebrew, Nix, Docker, and as a GitHub Action.

This is the beginning of the README. Read the rest at the original. Read the full README ↗