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High-performance code similarity detection tools written in Rust. Detects duplicate functions and similar code patterns across your codebase in multiple programming languages.

• Zero configuration - works out of the box
• Multi-language support - TypeScript/JavaScript, Python, and Rust
• Fast & Accurate - AST-based comparison, not just text matching
• AI-friendly output - Easy to share with Claude, GPT-4, etc.

cargo install similarity-ts

# Scan current directorysimilarity-ts.# Scan specific filessimilarity-ts src/utils.ts src/helpers.ts# Show actual codesimilarity-ts. --print

Copy the output and use this prompt with Claude:

Run `similarity-ts .` to detect semantic code similarities. Execute this command, analyze the duplicate code patterns, and create a refactoring plan. Check `similarity-ts -h` for detailed options.

Example output:

Duplicates in src/utils.ts:────────────────────────────────────────────────────────────  src/utils.ts:10-20 calculateTotal <-> src/helpers.ts:5-15 computeSum  Similarity: 92.50%, Score: 9.2 points

The AI will analyze patterns and suggest refactoring strategies.

• AI Assistant Guide - Refactoring workflow and best practices

• similarity-ts - TypeScript/JavaScript similarity detection ✅Most mature and production-tested

• similarity-py - Python similarity detection⚠️Not production-tested
• similarity-rs - Rust similarity detection⚠️Not production-tested

• similarity-elixir - Elixir similarity detection 🧪Experimental
• similarity-generic - Generic similarity detection for Go, Java, C/C++, C#, Ruby 🧪Experimental
• similarity-md - Markdown similarity detection 🧪Experimental

# Install from crates.iocargo install similarity-ts# Use the installed binarysimilarity-ts --help

# Install from crates.iocargo install similarity-py# Use the installed binarysimilarity-py --help

# Install from crates.iocargo install similarity-rs# Use the installed binarysimilarity-rs --help

# Install from crates.iocargo install similarity-elixir# Use the installed binarysimilarity-elixir --help

# Install from crates.iocargo install similarity-generic# Use the installed binarysimilarity-generic --language go main.gosimilarity-generic --language java Main.java

# Clone the repositorygit clone https://github.com/mizchi/similarity.gitcd similarity# Build all toolscargo build --release# Or install specific toolcargo install --path crates/similarity-tscargo install --path crates/similarity-pycargo install --path crates/similarity-rs

• --threshold /-t - Similarity threshold (0.0-1.0, default: 0.85)
• --min-lines /-m - Minimum lines for functions (default: 3-5)
• --min-tokens - Minimum AST nodes for functions
• --print /-p - Print code in output
• --cross-file /-c - Enable cross-file comparison
• --no-size-penalty - Disable size difference penalty

# Check for duplicate functions (default)similarity-ts ./src# Enable type checking (experimental)similarity-ts ./src --experimental-types# Check types onlysimilarity-ts ./src --no-functions --experimental-types# Fast mode with bloom filter (default)similarity-ts ./src --no-fast# disable

# Check Python filessimilarity-py ./src# Include test filessimilarity-py. --extensions py,test.py

# Check Rust filessimilarity-rs ./src# Skip test functions (test_ prefix or #[test])similarity-rs. --skip-test# Set minimum tokens (default: 30)similarity-rs. --min-tokens 50

The tool outputs in a VSCode-compatible format for easy navigation:

Duplicates in src/utils.ts:────────────────────────────────────────────────────────────  src/utils.ts:10 | L10-15 similar-function: calculateSum  src/utils.ts:20 | L20-25 similar-function: addNumbers  Similarity: 85.00%, Priority: 8.5 (lines: 10)

Click on the file paths in VSCode's terminal to jump directly to the code.

Results are sorted by priority (lines × similarity) to help you focus on the most impactful duplications first.

For AI assistants (like Claude, GPT-4, etc.) to help with code deduplication:

`similarity-ts .` でコードの意味的な類似が得られます。あなたはこれを実行し、ソースコードの重複を検知して、リファクタリング計画を立てます。細かいオプションは similarity-ts -h で確認してください。

English version:

Run `similarity-ts .` to detect semantic code similarities. Execute this command, analyze the duplicate code patterns, and create a refactoring plan. Check `similarity-ts -h` for detailed options.

1. Run similarity detection:

   similarity-ts. --threshold 0.8 --min-lines 10

2. Share output with AI: Copy the similarity report to your AI assistant

3. AI analyzes patterns: The AI will identify common patterns and suggest refactoring strategies

4. Iterative refinement: Adjust threshold and options based on AI recommendations

This tool can be integrated into:

• Pre-commit hooks to prevent duplicate code
• CI/CD pipelines for code quality checks
• IDE extensions for real-time duplicate detection
• AI-powered code review workflows

1. AST Parsing: Language-specific parsers convert code to ASTs
   • TypeScript/#"auto">

     Overlap Detection (Experimental)

# Basic overlap detectionsimilarity-ts ./src --experimental-overlap# With custom parameterssimilarity-ts ./src --experimental-overlap \  --threshold 0.75 \  --overlap-min-window 8 \  --overlap-max-window 25 \  --overlap-size-tolerance 0.25

Language-Specific Features

Examples

TypeScript/JavaScript

# Find duplicate functionssimilarity-ts ./src --threshold 0.7 --print# Find similar types across filessimilarity-ts ./src --no-functions --experimental-types --cross-file --print# Comprehensive analysissimilarity-ts ./src \  --threshold 0.8 \  --min-lines 10 \  --cross-file \  --extensions ts,tsx# Detect partial code overlaps (Experimental)similarity-ts ./src --experimental-overlap --threshold 0.75 --print

Python

# Find duplicate functions in Python projectsimilarity-py ./src --threshold 0.85 --print# Check with custom settingssimilarity-py. \  --min-lines 5 \  --extensions py

Rust

# Find duplicates excluding testssimilarity-rs ./src --skip-test --print# Strict checking with high token countsimilarity-rs. \  --min-tokens 50 \  --threshold 0.9 \  --skip-test

Experimental: Generic Language Support

similarity-generic

Installation

# From crates.io (when available)cargo install similarity-generic# From sourcecargo install --path crates/similarity-generic

Usage

# Detect Go duplicatessimilarity-generic --language go ./src# Detect Java duplicatessimilarity-generic --language java ./src# Detect C/C++ duplicatessimilarity-generic --language c ./srcsimilarity-generic --language cpp ./src# Detect C# duplicatessimilarity-generic --language csharp ./src# Detect Ruby duplicatessimilarity-generic --language ruby ./src# Detect Elixir duplicatessimilarity-generic --language elixir ./src# Common options work the same waysimilarity-generic --language go ./src --threshold 0.8 --print

Supported Languages

Custom Language Configuration

# Use custom config filesimilarity-generic --config ./my-language.json ./src

Limitations

Performance

License