Development
Plugin
jscpd
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.
Plugin Signal73/100Solid
maintained98
capable23
documented100
adopted80
Install
$ npx -y skills add kucherenko/jscpd --agent claude-code
Run the curl in your terminal, the rest in Claude Code.
Stats
5,982
Stars
253
Forks
Active
Maintenance
TypeScript
Language
MIT
License
3d ago
Last commit
13y ago
Created
Repo: kucherenko/jscpd
What's inside
Skills
2Badges
4
README
1jscpd
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) | Node.js engine — CLI, reporters, config, detection modes |
| Rust (v5.x) | Rust engine — installation, CLI, reporters, blame, Rust API |
| AI-Ready | AI reporter, agent skills, MCP server |
| Programming API | TypeScript and Rust programmatic APIs |
| CI & Pre-Commit Hooks | GitHub Action, pre-commit hooks |
| Packages | 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.jsonconfig 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)
- 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 for the full CLI reference and differences from v4.
v4.2.x — TypeScript Engine
- Custom tokenizer backend — replaced
prismjswith 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 for the full CLI reference.
Packages
| Package | Description |
|---|---|
| jscpd | CLI and Node.js API (v4.x) |
| jscpd-server | REST API + MCP server |
| @jscpd/core | Core detection algorithm |
| @jscpd/finder | File detection, reporters |
| @jscpd/tokenizer | Source code tokenization |
| @jscpd/html-reporter | HTML report |
| @jscpd/badge-reporter | SVG badge |
| jscpd-sarif-reporter | SARIF (GitHub Code Scanning) |
| @jscpd/leveldb-store | LevelDB persistent store |
| @jscpd/redis-store | Redis distributed store |
| cpd (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 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 for full details.
Contributing
- Fork the repo kucherenko/jscpd
- Clone forked version (
git clone https://github.com/{your-id}/jscpd) - Install dependencies (
pnpm install) - Run in dev mode:
pnpm dev - Add your changes
- Add tests and check:
pnpm test - Build:
pnpm build - Create PR
Backers
Thank you to all our backers! 🙏 [Become a backer]
Sponsors
Support this project by becoming a sponsor. Your logo will show up here with a link to your website. [Become a sponsor]
License
MIT © Andrey Kucherenko
File tree
1192kucherenko/jscpdView on GitHub
.changeset/
config.json
README.md
.editorconfig
.eslintrc.json
.github/
actions/
jscpd/
parse-output.js
CONTRIBUTING.md
dependabot.yml
FUNDING.yml
ISSUE_TEMPLATE/
bug_report.md
custom.md
feature_request.md
PULL_REQUEST_TEMPLATE.md
workflows/
crates-publish.yml
nodejs.yml
npm-rust-publish.yml
release-rust.yml
release.yml
rust.yml
.gitignore
.jscpd.json
.npmrc
.pre-commit-hooks.yaml
.prettierignore
action.yml
apps/
jscpd/
jscpd-server/
__tests__/
mcp-server.test.ts
server.test.ts
.npmignore
bin/
jscpd-server
jscpd-server.ts
CHANGELOG.md
nodemon.json
package.json
README.md
src/
detect.ts
index.ts
server/
constants.ts
ephemeral-store.ts
index.ts
mcp-server.ts
middleware.ts
routes.ts
server.ts
service.ts
types/
index.ts
requests.ts
responses.ts
state.ts
setup/
cli-utils.ts
hooks.ts
ignore.ts
index.ts
options.ts
reporters.ts
store.ts
subscribers.ts
tsconfig.build.json
tsconfig.json
tsup.config.ts
__tests__/
cli-parsing.test.ts
formats.test.ts
ignore.test.ts
modes.test.ts
options-unit.test.ts
options.test.ts
print.test.ts
reporters.test.ts
store.test.ts
.npmignore
bin/
jscpd
jscpd.ts
CHANGELOG.md
LICENSE
nodemon.json
package.json
README.md
src/
index.ts
init/
cli.ts
hooks.ts
ignore.ts
index.ts
options.ts
reporters.ts
store.ts
subscribers.ts
options.ts
print/
files.ts
index.ts
options.ts
supported-format.ts
tsconfig.build.json
tsconfig.json
tsup.config.ts
vitest.config.ts
assets/
jscpd-badge.svg
logo-small-box.svg
logo-small.svg
logo.svg
screenshot-1.png
screenshot-2.png
screenshot.png
benchmark/
.gitignore
BENCHMARK.md
benchmark.sh
tools/
package-lock.json
package.json
README.md
build-utils/
prismjs-languages-concat.ts
publish-util.ts
CHANGELOG.md
CODE_OF_CONDUCT.md
docs/
ai-ready.md
api.md
ci-and-hooks.md
packages.md
performance-comparison.md
rust.md
typescript.md
examples/
api/
example_github_action.yml
example-detectClones.ts
example-jscpd.ts
example-persist-store.ts
fixtures/
.jscpd.json
actionscript/
file1.as
file2.as
ada/
file1.ada
file2.ada
antlr4/
file1.g4
file2.g4
apex/
file1.cls
file2.cls
apl/
file1.apl
file1.dyalog
file2.apl
file2.dyalog
astro/
component1.astro
component2.astro
awk/
file1.awk
file2.awk
basic/
file1.bas
file2.bas
bicep/
file1.bicep
file2.bicep
brainfuck/
file1.b
file1.bf
file2.b
file2.bf
cfml/
file1.cfm
file2.cfm
cfscript/
file1.cfc
file2.cfc
clike/
file1.c
file1.c++
file1.cc
file1.cpp
file1.cs
file1.cxx
file1.h
file1.h++
file1.hh
file1.hpp
file1.hxx
file1.java
file1.kt
file1.m
file1.mm
file1.nut
file1.scala
file2.c
file2.c++
file2.cc
file2.cpp
file2.cs
file2.cxx
file2.h
file2.h++
file2.hh
file2.hpp
file2.hxx
file2.java
file2.kt
file2.m
file2.mm
file2.nut
file2.scala
clojure/
file1.clj
file1.cljc
file1.cljs
file1.cljx
file1.edn
file2.clj
file2.cljc
file2.cljs
file2.cljx
file2.edn
cmake/
file1.cmake
file1.cmake.in
file2.cmake
file2.cmake.in
cobol/
file1.cob
file1.cpy
file2.cob
file2.cpy
coffeescript/
file1.coffee
file2.coffee
commonlisp/
file1.cl
file1.el
file1.lisp
file2.cl
file2.el
file2.lisp
cross-formats/
a.ts
b.js
crystal/
file1.cr
file2.cr
css/
file1.css
file1.gss
file1.less
file1.scss
file10.css
file2.css
file2.gss
file2.less
file2.scss
csv/
file1.csv
file2.csv
custom/
file.cc1
file.ccc
cypher/
file1.cyp
file1.cypher
file2.cyp
file2.cypher
d/
file1.d
file2.d
dart/
file1.dart
file2.dart
diff/
file1.diff
file1.patch
file2.diff
file2.patch
dot/
file1.dot
file2.dot
dtd/
file1.dtd
file2.dtd
dylan/
file1.dyl
file1.dylan
file1.intr
file2.dyl
file2.dylan
file2.intr
ecl/
file1.ecl
file2.ecl
eiffel/
file1.e
file2.e
elm/
file1.elm
file2.elm
erlang/
file1.erl
file2.erl
factor/
file1.factor
file2.factor
folder1/
file_1.js
file2.c
folder2/
file_2.js
forth/
file1.4th
file1.forth
file1.fth
file2.4th
file2.forth
file2.fth
fortran/
file1.f
file1.f77
file1.f90
file1.for
file2.f
file2.f77
file2.f90
file2.for
gas/
file1.s
file2.s
gdscript/
file1.gd
file2.gd
gettext/
file1.po
file2.po
gherkin/
file1.feature
file2.feature
gitignore/
file1.gitignore
file2.gitignore
go/
file1.go
file2.go
graphql/
file1.graphql
file2.graphql
groovy/
file1.gradle
file1.groovy
file2.gradle
file2.groovy
haml/
file1.haml
file2.haml
handlebars/
file1.hbs
file2.hbs
haskell/
haskell-literate/
file1.lhs
file2.lhs
file1.hs
file2.hs
haxe/
file1.hx
file1.hxml
file2.hx
file2.hxml
hcl/
file1.tf
file2.tf
htmlembedded/
file1.aspx
file1.ejs
file1.erb
file1.jsp
file2.aspx
file2.ejs
file2.erb
file2.jsp
htmlmixed/
file1.htm
... 1060 moreFAQ
jscpd is a Claude Code plugin with 2 hand-picked skills for development work, indexed on Flowy. Install it with the command on its page. It includes dry-refactoring, jscpd. Its skills do not fire on their own yet. Request auto-invocation to have Flowy route them as you prompt. Free and open source.
- What is jscpd?
- 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.
- How do I install jscpd?
- Run these in Claude Code: npx -y skills add kucherenko/jscpd --agent claude-code. Then prompt normally.
- Does jscpd auto-invoke its skills?
- Not yet. It is indexed on Flowy as a plain plugin. Request auto-invocation on its page and Flowy will route its skills for you as you prompt.
- Is jscpd free?
- Yes. Flowy is free and open source, with nothing gated. You can read every skill in full before you install.