jscpdv5

Copy/Paste Detector for Source Code

jscpd v5 is a Rust-powered rewrite that hunts down duplicated blocks across 223+ languages up to 37x faster than v4 — because life's too short to maintain the same bug in five different places. Need the Node.js API? v4 is still available. AI-ready with the --reporters ai flag.
Hunt DuplicatesSponsor the project
Terminal
$curl -fsSL https://jscpd.dev/install.sh | bash
// Your code deserves better than copy/paste chaos
$jscpd./src
→ Finding duplicates...
✓ Scan complete: 3 clones found

Why Developers Love jscpd

Because clean code is happy code
    Since 2013
    A decade of refining the art of duplicate detection. Now rewritten in Rust for native performance — no Node.js runtime required.
    Speaks 223+ Languages

    JavaScript, Python, Java, Go, Rust, C++, TypeScript, Ruby... If you can write it, we can scan it. Vue, Svelte, Astro, and Markdown cross-format detection too.

    View supported formats →
    20M+ Downloads
    One of the most trusted tools in the ecosystem. Join developers who rely on jscpd every day.
    Blazingly Fast™

    Rewritten in Rust. 24-37x faster than the TypeScript engine. 159 MB codebase? 3.4 seconds. No Node.js runtime — just a single native binary.

    See benchmarks →
    CLI-First Design

    One command to rule them all. Works everywhere — your laptop, CI/CD, that ancient Jenkins server nobody wants to touch.

    Get started →
    Beautiful Reports

    HTML, JSON, XML, badges for your README. Make technical debt visible (and slightly embarrassing).

    Explore reporters →
    Programmable

    v5: Rust crate API. v4: Node.js API. Same CLI in both. Use whichever fits your stack.

    View API documentation →
    CI/CD Ready

    Set a threshold, fail the build, save the day. Your future self will thank you.

    Configure thresholds →
    MCP Server New

    Let AI assistants like Claude check your code for duplications directly using the Model Context Protocol.

    Learn about MCP Server →
    Cross-Format Detection New
    Vue SFC, Svelte, Astro, and Markdown files are tokenized per-block — a <script> in .vue can match a .ts file. Detect duplication across file types.
    AI Reporter New

    Compact output that saves ~79% of tokens compared to the default reporter — ideal for piping into LLMs.

    AI Reporter docs →
    Agent Skill New

    Install a skill for your AI coding assistant to automatically detect and refactor duplications — one command to get started.

    npx skills add kucherenko/jscpd
    Learn more →

See It In Action

From chaos to clarity in seconds
# Scan your source code
$ jscpd ./src

Clone found (typescript):
 - src/utils.ts [10:1 - 25:3] (15 lines, 129 tokens)
    src/helpers.ts [5:1 - 20:3]

Clone found (typescript):
 - src/utils.ts [45:5 - 62:2] (17 lines, 178 tokens)
    src/components/Button.tsx [12:1 - 29:2]

Clone found (javascript):
 - src/hooks/useAuth.ts [1:1 - 34:2] (33 lines, 245 tokens)
    src/hooks/useSession.ts [1:1 - 34:2]

# ... more clones

Found 90 clones.
Detection time: 13ms

v5 vs v4: Performance

The Rust engine makes jscpd 24–37x faster across every codebase size.
TargetFilesSizev4 (TypeScript)v5 (Rust)Speedup
fixtures5481.5 MB1.03s0.03s34.3x
Svelte8,96338 MB15.80s0.43s36.9x
CopilotKit17,092159 MB82.89s3.44s24.1x

Git blame is 27.5x faster with v5's in-process gitoxide (0.13s vs 3.57s on fixtures).

Benchmarked on macOS (Apple Silicon). See the Migration Guide for full details.

Built by a Human Who Gets It

Created with ❤️ by Andrey Kucherenko

Andrey Kucherenko believes that every copy-pasted code block is a bug waiting to happen twice. He built jscpd so you don't have to fix the same issue in five files.

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💙 Huge Thank You to Our Contributors!

This project wouldn't exist without you

To everyone who has contributed to jscpd — thank you! 🌟

Whether you've submitted code, reported bugs, suggested features, improved documentation, or simply spread the word — your contributions make jscpd better for everyone. We're grateful for every issue closed, every PR merged, and every kind word shared.

With a grateful heart, 🤗

The jscpd Team

View Contributors