kucherenko/jscpd

Copy/paste detector for programming source code, supports 223 formats. AI-ready with token-efficient reporter, skill and MCP server.

Source code at GitHub https://jscpd.dev/

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  "createdAt": "2013-05-29T06:19:20Z",
  "defaultBranch": "master",
  "description": "Copy/paste detector for programming source code, supports 223 formats. AI-ready with token-efficient reporter, skill and MCP server.",
  "fullName": "kucherenko/jscpd",
  "homepage": "https://jscpd.dev/",
  "language": "TypeScript",
  "name": "jscpd",
  "pushedAt": "2026-07-11T01:18:33Z",
  "stargazersCount": 5870,
  "topics": [
    "ai",
    "clones-detection",
    "code-quality",
    "coding-agents",
    "copy-paste",
    "copy-paste-detection",
    "cpd",
    "detector",
    "dry",
    "duplicates",
    "duplications",
    "mcp",
    "quality",
    "skill",
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  "updatedAt": "2026-07-12T12:08:06Z",
  "url": "https://github.com/kucherenko/jscpd"
}

jscpd

NPM License

Copy/paste detector for programming source code. Supports 224+ formats. AI-ready with MCP server and token-efficient reporter. Now with a Rust-powered engine — 24-37x faster.

jscpd implements the Rabin-Karp algorithm to find duplicated code blocks across files.

Quick Start

# Install (all platforms — installs the jscpd command)
curl -fsSL https://jscpd.dev/install.sh | bash

# TypeScript engine (Node.js, v4.x)
npm install -g jscpd@4
jscpd /path/to/code
# or use without installing
npx jscpd@4 /path/to/code

# Rust engine (v5.x, 24-37x faster) — installs the jscpd command
npm install -g jscpd@5
jscpd /path/to/code

# Rust engine — cpd command only
npm install -g cpd
cpd /path/to/code

# Rust-native install (exposes both jscpd and cpd)
cargo install jscpd

# Nix (installs both jscpd and cpd)
nix run github:kucherenko/jscpd -- /path/to/code
# or install permanently
nix profile install github:kucherenko/jscpd

# Homebrew (macOS/Linux)
brew install jscpd

Documentation

Document	Description
[TypeScript (v4.x)]!(docs/typescript.md)	Node.js engine — CLI, reporters, config, detection modes
[Rust (v5.x)]!(docs/rust.md)	Rust engine — installation, CLI, reporters, blame, Rust API
[AI-Ready]!(docs/ai-ready.md)	AI reporter, agent skills, MCP server
[Programming API]!(docs/api.md)	TypeScript and Rust programmatic APIs
[CI & Pre-Commit Hooks]!(docs/ci-and-hooks.md)	GitHub Action, pre-commit hooks
[Packages]!(docs/packages.md)	Monorepo package and crate overview

Two Engines

	TypeScript (v4)	Rust (v5)
npm package	`jscpd@4`	`jscpd@5` or `cpd`
CLI command	`jscpd`	`jscpd` (from `jscpd@5`) or `cpd` (from `cpd`)
Speed	Baseline	24-37x faster
Formats	224	223
Node.js required	Yes	No (self-contained binary)
Programming API	TypeScript (`jscpd()`, `detectClones()`)	Rust (`cpd-finder` crate)
LevelDB store	Yes	No
Reporters	13	13

jscpd@5 installs the jscpd command. The cpd npm package installs the cpd command. Both contain the same Rust binary. For both command names from a single install, use crates.io: cargo install jscpd.

What’s New

v5.0.x — Rust Engine

jscpd v5 is a ground-up Rust rewrite that ships as jscpd@5 (installs the jscpd command) or cpd (installs the cpd command). Self-contained binary — no Node.js runtime required.

Same interface, 24-37x faster:

All CLI options from v4 are preserved — drop-in replacement: jscpd → jscpd@5
Same .jscpd.json config file, same detection algorithm, same reporters
223 language formats with cross-format detection (Vue SFC, Svelte, Astro, Markdown)

New in v5:

24-37x faster detection on real projects (see [benchmark]!(docs/performance-comparison.md))
- Small codebases (548 files): 34x faster
- Medium codebases (9K files): 37x faster
- Large codebases (17K files, 900 MB): 24x faster
Git blame with side-by-side author comparison (--blame --reporters console-full)
--workers — control parallelism for file tokenization and detection (default: auto, uses all CPU cores; not available in v4)
13 reporters: console, console-full, json, xml, csv, html, markdown, badge, sarif, ai, xcode, threshold, silent
AI reporter — token-efficient output for LLM pipelines (~79% fewer tokens than console)
Self-contained binary — prebuilt for 6 platforms (macOS arm64/x64, Linux arm64/x64, Windows x64)

Not yet in v5 (use v4 for these):

LevelDB/Redis stores (--store leveldb)
Node.js programming API (jscpd(), detectClones())

See [Rust docs]!(docs/rust.md) for the full CLI reference and differences from v4.

v4.2.x — TypeScript Engine

Custom tokenizer backend — replaced prismjs with own backend built on reprism. ~11.5% faster tokenization on real projects
Cross-format detection — Vue SFC, Svelte, Astro, and Markdown tokenized per-block, enabling detection across file types
New formats: Apex, CFML/ColdFusion, GDScript, and 70+ additional formats (224 total, up from 152)
Shebang detection — auto-detect language for extensionless scripts
--store-path — configure LevelDB cache directory for parallel runs
--skipComments — shorthand for --mode weak
--formats-names — map filenames (e.g. Makefile, Dockerfile) to formats
--noTips — suppress tip output in CI
Bug fixes: entire-file duplicates silently dropped (#728), ReDoS on Lisp/Elisp files (#737), process crash on malformed package.json (#739), Vue SFC cross-file detection (#737), Vue SFC column numbers (#737), 50 dependency security vulnerabilities

See [TypeScript docs]!(docs/typescript.md) for the full CLI reference.

Packages

Package	Description
[jscpd]!(apps/jscpd)	CLI and Node.js API (v4.x)
[jscpd-server]!(apps/jscpd-server)	REST API + MCP server
[@jscpd/core]!(packages/core)	Core detection algorithm
[@jscpd/finder]!(packages/finder)	File detection, reporters
[@jscpd/tokenizer]!(packages/tokenizer)	Source code tokenization
[@jscpd/html-reporter]!(packages/html-reporter)	HTML report
[@jscpd/badge-reporter]!(packages/badge-reporter)	SVG badge
[jscpd-sarif-reporter]!(packages/sarif-reporter)	SARIF (GitHub Code Scanning)
[@jscpd/leveldb-store]!(packages/leveldb-store)	LevelDB persistent store
[@jscpd/redis-store]!(packages/redis-store)	Redis distributed store
[cpd]!(rust) (Rust engine)	Rust-powered engine (v5.x) — also available as `jscpd@5`

Who Uses jscpd

GitHub Super Linter — official GitHub linter aggregator, bundles jscpd as its copy/paste detector
Codacy — automated code analysis platform, jscpd powers the duplication engine
MegaLinter — 100% open-source linter aggregator for CI, integrates jscpd
OpenClaw — personal AI assistant for self-hosted devices
Natural — NLP library for Node.js, uses jscpd for code quality

Performance

Benchmarked on macOS (Apple Silicon), 10 runs per target (3 for CopilotKit). v4 ran with --no-gitignore -i "node_modules" to ensure comparable file scanning.

Target	Files	Size	jscpd v4	jscpd v5	Speedup
fixtures	548	1.5 MB	1.03s	0.03s	34.3x
svelte	9K	38 MB	15.80s	0.43s	36.9x
CopilotKit	17K	159 MB	82.89s	3.44s	24.1x

See [performance-comparison.md]!(docs/performance-comparison.md) for full methodology and raw data.

AI-Ready Features

jscpd integrates into AI-powered workflows through three mechanisms:

AI Reporter

Token-efficient output for LLM pipelines (~79% fewer tokens than the default console reporter):

jscpd --reporters ai /path/to/source   # v4
cpd --reporters ai /path/to/source      # v5

Agent Skills

Two installable skills that teach AI coding assistants how to use jscpd and refactor detected duplications:

Skill	Purpose	Install
`jscpd`	Tool reference — CLI options, AI reporter format, config syntax	`npx skills add kucherenko/jscpd --skill jscpd`
`dry-refactoring`	Guided refactoring workflow — read clones, choose strategy, apply, verify	`npx skills add kucherenko/jscpd --skill dry-refactoring`

After installation, ask your agent to “find and fix code duplication” and it will invoke jscpd with the right options and act on the results.

See [AI-Ready docs]!(docs/ai-ready.md) for full details.