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On the recordRead 5 Oct 202620 facts

QuickDup

Huddinge, Sweden

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What it is

QuickDup is a free, open-source repository tool for finding candidate code clones through indentation-based fingerprints. It records indentation changes and the first word on each line, skips comments and blank lines, tokenizes source lines, and filters patterns with Jaccard similarity below a default 75% threshold. It does not parse abstract syntax trees. Detection strategies include normalized-indent, word-indent, word-only, and inlineable. Listed language support covers Go, C and C++, Java, JavaScript and TypeScript, C#, Python, Ruby, SQL, Lua, MATLAB, and others. Results are saved as machine-readable JSON in a .quickdup directory. QuickDup can emit GitHub Actions annotations for inline pull request comments and restrict annotations to files changed against a Git reference. Incremental parsed-file caching is available only for word-indent; other strategies re-parse files each run. The README reports about 100,000 lines processed in about 500 ms on 8 cores. Installers are listed for Linux, macOS, and Windows, with source installation through Go. The latest listed release is v0.6.0.

For and against

For

  • Supports multiple indentation-based strategies
  • Produces machine-readable JSON results
  • GitHub Actions annotations for pull requests
  • Runs on Linux, macOS, and Windows
  • MIT-licensed open-source project

Against

  • Heuristics can produce false positives
  • May miss semantically duplicate code with different structure
  • Only word-indent supports incremental caching
  • No IDE integration listed

The verdict

QuickDup is designed to surface code-clone candidates quickly for later judgment by an AI agent and human reviewer. Its heuristic method, caching limitation, and lack of IDE integration define the main trade-offs.

Who it suits

QuickDup suits development teams and individuals who want heuristic duplicate-code candidates for AI-assisted or human review. It fits repositories using GitHub Actions and supported languages.

On the record

Caching
Incremental caching is available only for the word-indent strategy; the other listed strategies re-parse files on each run.github.com · read 4 Oct 2026
Caching limit
Incremental parsed-file caching is supported only by the word-indent strategy; the other listed strategies re-parse files on each run.github.com · read 5 Oct 2026
Detection approach
QuickDup fingerprints indentation changes and the first word on each line, and does not use AST parsing.github.com · read 4 Oct 2026
Detection strategies
It offers normalized-indent, word-indent, word-only, and inlineable detection strategies.github.com · read 5 Oct 2026
GitHub Actions integration
It can emit GitHub Actions annotations for inline pull request comments and can limit annotations to files changed against a Git reference.github.com · read 5 Oct 2026
GitHub integration
QuickDup can emit GitHub Actions annotations for inline pull request comments and limit annotations to files changed against a Git reference.github.com · read 4 Oct 2026
How it works
It fingerprints indentation changes and the first word on each line, skips comments and blank lines, and detects patterns without AST parsing.github.com · read 5 Oct 2026
Installation
The README provides installer commands for Linux and macOS, a PowerShell installer for Windows, and installation from source with Go.github.com · read 4 Oct 2026
Intended use
It is designed to generate candidate duplicates for AI-assisted code review, with an AI agent and human decision maker verifying candidates.github.com · read 4 Oct 2026
Languages
The README lists comment-prefix support for languages including Go, C/C++, Java, JavaScript/TypeScript, C#, Python, Ruby, SQL, Lua, and others.github.com · read 5 Oct 2026
Language support
The README lists comment-prefix detection for languages including Go, C#, JavaScript, TypeScript, Python, Ruby, SQL, Lua, and MATLAB, among others.github.com · read 4 Oct 2026
License
QuickDup is released under the MIT License.github.com · read 5 Oct 2026
Limitations
The project describes QuickDup as a heuristic candidate generator that can produce false positives and miss semantically duplicate code with different structure.github.com · read 5 Oct 2026
Maker location
The maker's GitHub organization profile lists Stockholm, Sweden.github.com · read 5 Oct 2026
Output
Results are written as machine-readable JSON files in a .quickdup directory.github.com · read 5 Oct 2026
Performance
The README reports scanning about 100,000 lines of code in about 500 ms on 8 cores.github.com · read 5 Oct 2026
Purpose
QuickDup is a structural code clone detector that finds duplicate code patterns using indent-delta fingerprinting and is designed to generate candidates for AI-assisted code review.github.com · read 5 Oct 2026
Release
The GitHub releases page lists v0.6.0 as the latest release.github.com · read 5 Oct 2026

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