dcd

Summary

dcd is a free duplicate-code detector that scans a repository to find repeated code. Its language-aware parsing, provided via scc, covers 250+ languages. Matching can go beyond identical lines: the --fuzz option uses simhash distance for similar lines, while gap and hole tolerance options account for changes within otherwise matching blocks. The --file option checks one file against the rest of a codebase. Results can be shown as PBM scatter plots or self-contained interactive HTML reports with file heatmaps and scatter plots, or emitted as structured JSON for other tools and CI pipelines. dcd can read .ignore files using .gitignore-style syntax and skip marked code blocks. It is available for Linux and macOS under the GNU Affero General Public License 3.0. Installation requires Go 1.19 or newer. Release 1.1.0 removed Windows support for full filesystem compatibility; Windows users are directed to WSL. Commercial users can buy a year's priority support entitlement for direct email support from the developer, though no price is listed.

Who it is for

dcd suits developers who want repository-level duplicate-code scans, including use in CI pipelines. It also fits users who need visual reports or structured output and can use Linux or macOS, or WSL on Windows.

Compared on code clone detection tools

Free plan

Yesgithub.com

Clone detection method

textgithub.com

Scan scope

repositorygithub.com

CI integration

Yesgithub.com

IDE integration

Nogithub.com

Self-hosted option

Yesgithub.com

Facts

Purpose

dcd is a duplicate code detector designed to identify duplicate code within a project.github.com · 30 Sept 2026

License

The project is licensed under the GNU Affero General Public License 3.0.github.com · 30 Sept 2026

Fuzzy matching

The --fuzz option uses simhash distance to match similar but non-identical lines, with values from 0 to 255.github.com · 30 Sept 2026

Gap tolerance

The --gap-tolerance option bridges inserted, deleted, or modified lines in otherwise matching duplicate blocks.github.com · 30 Sept 2026

Hole tolerance

The --max-hole-size option allows modified lines within a duplicate diagonal match.github.com · 30 Sept 2026

Single-file comparison

The --file option compares one file against the rest of the codebase.github.com · 30 Sept 2026

Visualizations

dcd can generate PBM scatter plots and self-contained interactive HTML reports with file heatmaps and scatter plots.github.com · 30 Sept 2026

Structured output

The --format json option produces structured JSON output for integration with other tools or CI pipelines.github.com · 30 Sept 2026

Ignore support

dcd supports .ignore files using the same syntax as .gitignore files and can ignore marked code blocks.github.com · 30 Sept 2026

Language coverage

The comparison table says dcd provides language-aware parsing via scc for 250+ languages.github.com · 30 Sept 2026

Installation

Users with Go 1.19 or newer can install dcd with go install github.com/boyter/dcd@latest.github.com · 30 Sept 2026

Release limitation

Release 1.1.0 removed Windows support for full filesystem compatibility and directs Windows users to WSL.github.com · 30 Sept 2026

Commercial support

Commercial users can purchase a year's priority support entitlement for direct email support from the developer.github.com · 30 Sept 2026

Maker background

Ben Boyter describes himself as a professional software engineer with more than 15 years of development experience focused on testing.boyter.org · 30 Sept 2026

Where it ranks on Everything Xiaomi

• Best Code Clone Detection Tools in 2026#6 of 23

Sources

• github.com/boyter/dcd· checked 30 Sept 2026
• github.com/boyter/dcd/releases· checked 30 Sept 2026
• boyter.org/about/· checked 30 Sept 2026