Duplo review
A focused, free CLI scanner for finding duplicated source blocks across repositories.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
Duplo is an open-source command-line tool for detecting duplicated code blocks across source files and large codebases. It suits developers and teams that want a free, self-hosted scanner for repository-wide checks without adopting a paid service. Duplo can analyze source files in several programming languages, apply language-aware filtering to comments and compiler directives, and examine arbitrary text files. Its cross-platform availability makes it practical for Windows, macOS, and Linux environments.
The tool fits automation-oriented workflows through file lists, standard-input filename streams, configurable minimum duplicate sizes, and multithreaded scanning. Results can be exported as JSON or XML, with stylesheet support for XML output. A separate GitHub Action supports automated repository scans, giving teams a direct path to include duplicate-block checks in GitHub Actions workflows. These options make Duplo more adaptable than a single interactive scan command, particularly when results need to move into scripts or reporting processes.
Duplo is intentionally focused on source-text comparison rather than a deeper analysis experience. Its text-based clone method can identify duplicate source blocks after language-specific filtering, but its detection depth is less detailed than higher-ranked tools. The command-line emphasis may also be a weaker fit for teams that expect a visual interface or broader platform integrations. Choose Duplo when free, open-source, self-hosted scanning and straightforward automation are the priorities; choose another tool when richer detection detail or a wider ecosystem matters more.
Duplo pros and cons
- Where it wins
- Filters comments and compiler directives by language.
- Exports scan results as JSON or XML with stylesheet support.
- Runs on Windows, macOS, and Linux with multithreaded scanning.
- Where it doesn't
- Its documented workflow is command-line based rather than visual.
- Text-based matching provides less detection depth than higher-ranked tools.
- Automation centers on GitHub Actions rather than a broad integration set.
Duplo fact sheet, pricing and score →
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