Duplo

7.1easy start · #4 of 23
in Code Clone Detection Tools

Free to practise onyes
Free trialnot on record
Well documentedyes
Runs where you workyes

Runs on Linux, Mac, Windows.

Duplo is ranked #4 of 23 in code clone detection tools on The Geeks Club. It runs on Linux, macOS, Windows. There is a free plan.

Duplo plans and pricing

All plans

Duplo Free Free software under GNU GPL v2 or later · prebuilt binaries for Alpine Linux, macOS and Windows github.com · 29 Sept 2026

Compared on code clone detection tools

Free plan: Yes
Clone detection method: text
Scan scope: repository
CI integration: Yes
Self-hosted option: Yes

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The record

Purpose: Duplo finds duplicated source code blocks in large codebases.
Language support: It has built in support for C/C++, Java, C#, VB, GCC assembly, Ada, Erlang, TypeScript and Swift, and can also scan arbitrary text files.
Filtering: For supported languages, Duplo can remove comments, preprocessor directives and other syntax before checking for duplicate code.
Reports: It can produce JSON and XML output as well as text reports.
GitHub Actions: The maker links a GitHub Action that can fail a build when duplicate blocks are found.
Action limits: The linked GitHub Action has configurable minimum duplicate lines and minimum line length, and a maximum number of files to report.
Performance: The README reports processing Quake2's 266 files and 102,740 lines in 9 seconds on modern hardware in 2025, and says multithreading can improve performance almost linearly.
Downloads: Pre-built binaries are available for Alpine Linux, macOS and Windows, and the project can also be built from source.
Support: The README directs users to open an issue for feedback, feature requests and bug reports.
License: Duplo is free software under GNU GPL version 2 or, at the user's option, any later version.
Caveat: The license section says Duplo is provided without warranty, including implied warranties of merchantability or fitness for a particular purpose.
Text files: Duplo can detect duplicates in arbitrary text files, including duplicates within a single file.
Input: Files can be supplied through standard input or a separate file containing the file list.
Limit: The README's quick-start example requires at least 20 lines for a duplicate, though command-line options can be adjusted.
Price from: Free

Where it ranks on The Geeks Club

Best Code Clone Detection Tools in 2026#4 of 23

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Sources

github.com/dlidstrom/Duplo· checked 28 Sept 2026
github.com/dlidstrom/duplo-analyser· checked 28 Sept 2026