copydetect vs QuickDup

copydetect is a free tool for comparing code directories and producing an HTML report that highlights matching code slices. It uses Winnowing document fingerprinting, an approach also used by MOSS, and Pygments tokenization for the 500-plus languages Pygments can detect and tokenize. Users can compare test directories with reference directories such as previous submissions, and exclude boilerplate directories from matches. Noise, guarantee and display thresholds adjust what is detected and shown in reports. Install the package with pip; it requires Python 3.7 or later. The command-line tool recursively searches supplied directories, while its Python API supports comparisons and HTML report generation. Reports can be saved to a specified path, highlighted code can be truncated, and custom CSS can be linked. Configuration is available through command-line arguments or a JSON file. The package is MIT-licensed and classified for Education with Beta development status. Its documentation cautions that it may not catch plagiarism designed to evade detection and that a match does not establish that plagiarism occurred.

QuickDup is a repository code clone detector that finds candidate duplicate patterns using changes in indentation and the first word on each line. It skips comments and blank lines, tokenizes source lines and uses Jaccard similarity to filter patterns below a default 75% threshold. It does not parse abstract syntax trees. Detection options include normalized-indent, word-indent, word-only and inlineable strategies. The README lists comment-prefix detection for languages including Go, C and C++, Java, JavaScript and TypeScript, C#, Python, Ruby, SQL, Lua and MATLAB. QuickDup can emit GitHub Actions annotations for inline pull request comments and restrict them to files changed against a Git reference. Results are written as machine-readable JSON in a .quickdup directory. Incremental caching is available only for the word-indent strategy; other listed strategies re-parse files on each run. The README reports processing about 100,000 lines in about 500 ms on 8 cores. QuickDup is free under the MIT License, with installers for Linux, macOS and Windows, or installation from source with Go.