jscpd — Copy/Paste Detector

jscpd v5.x is the Rust-based implementation. For the TypeScript/Node.js version, see jscpd v4.x.

Fast copy/paste detector for programming source code. 24-37x faster than the Node.js version. Supports 223 language formats, git blame, and 13 output reporters.

Packages

| Package | Version | Installs | When to use | |---------|---------|----------|-------------| | jscpd | 4.x | jscpd | Need the Node.js API, LevelDB/Redis stores, or programmatic usage | | jscpd | 5.x | jscpd and cpd | Maximum speed, CLI-only usage, or git blame | | cpd | 5.x | cpd | Same binary as jscpd 5.x, shorter command name only |

Both jscpd v5 and cpd v5 install the same Rust binary. Installing jscpd@5 gives you both jscpd and cpd commands.

Performance

| Codebase | Files | Size | jscpd v4 (Node.js) | jscpd v5 (Rust) | Speedup | |----------|-------|------|--------------------|-----------------|---------| | Multi-format fixtures | 548 | 1.5 MB | 1.03 s | 0.03 s | 34.3× | | Svelte source | 9K | 38 MB | 15.80 s | 0.43 s | 36.9× | | CopilotKit | 17K | 159 MB | 82.89 s | 3.44 s | 24.1× |

See performance-comparison.md for full methodology and raw data.

Install

# npm — installs both jscpd and cpd commands
npm install -g jscpd

# or install just the cpd command
npm install -g cpd

# crates.io — installs both jscpd and cpd binaries
cargo install jscpd

# Nix — run without installing
nix run github:kucherenko/jscpd -- /path/to/code

# Nix — install permanently
nix profile install github:kucherenko/jscpd

# Homebrew (macOS/Linux)
brew install jscpd

Prebuilt binaries for 6 platforms — no Node.js runtime required.

Quick Start

# Scan current directory
jscpd .
cpd .           # same command, shorter name

# Git blame with side-by-side author comparison
jscpd . --blame --reporters console-full

# Output to JSON + HTML
jscpd . --reporters json,html

# Fail CI if duplication exceeds threshold
jscpd . --threshold 10

# List all supported formats
jscpd --list

Options

| Flag | Short | Default | Description | |------|-------|---------|-------------| | --min-tokens | -k | 50 | Minimum tokens to consider a duplicate | | --min-lines | -l | 5 | Minimum lines to consider a duplicate | | --max-lines | -x | — | Maximum lines per duplicate block | | --mode | -m | mild | Detection mode: mild, weak, strict | | --skip-comments | — | — | Alias for --mode weak | | --format | -f | all | Comma-separated formats to check | | --ignore-pattern | -i | — | Glob patterns to ignore | | --reporters | -r | console | Comma-separated reporters | | --output | -o | report | Output directory for file reporters | | --config | -c | — | Path to config file (.jscpd.json) | | --threshold | -t | — | Max duplication % before exit 1 | | --blame | -b | — | Enrich clones with git blame data | | --skip-local | — | — | Skip clones within the same directory | | --silent | -s | — | Suppress console output | | --list | — | — | List all supported formats and exit |

For the full options list, see docs/rust.md.

Reporters

| Reporter | Output | |----------|--------| | console | Clone list + statistics table (default) | | console-full | Source snippets + blame comparison | | json | report/jscpd-report.json | | html | report/jscpd-report.html | | sarif | report/jscpd-report.sarif (GitHub Code Scanning) | | ai | Token-efficient output for LLM pipelines | | badge | report/jscpd-badge.svg + report/jscpd-lines-badge.svg |

Plus: xml, csv, markdown, xcode, threshold, silent.

Config File

Create .jscpd.json in your project root:

{
  "minTokens": 30,
  "minLines": 3,
  "format": ["javascript", "typescript", "python"],
  "ignorePattern": ["node_modules", "dist", "*.min.js"],
  "reporters": ["console", "json"],
  "output": "report",
  "threshold": 5,
  "blame": false
}

Cross-Format Detection

Vue SFC (.vue), Svelte (.svelte), Astro (.astro), and Markdown files are tokenized per-block, enabling duplicate detection across file types.

Known Differences from jscpd v4

| Feature | jscpd v4 (Node.js) | jscpd v5 (Rust) | |---------|--------------------|-------------------| | --store (LevelDB) | Persistent store for large repos | Not supported | | Programming API | jscpd() Promise API, detectClones() | Rust crate API; no Node.js API | | --reporters | All v4 reporters | All except full (use console-full) |

See docs/rust.md for the full differences table and detailed documentation.

License

MIT