Fallow vs phpcpd-next

Fallow has no write-up on Specifiction yet; its figures are above.

phpcpd-next is a free, MIT-licensed, token-based detector for copied PHP code in repositories. It targets PHP 8.4 and later and succeeds Sebastian Bergmann’s phpcpd. The default run combines Rabin-Karp exact matching with TokenBag detection for reordered code. An opt-in unified engine detects exact, renamed, gapped and reordered clones, while optional orphan mode identifies unreferenced classes, interfaces, traits, enums and functions. Results can be printed to the console or written as PMD-CPD XML, JSON and SARIF 2.1.0. Meaningful exit codes, result caching and a per-file incremental index support continuous integration; clone findings return status 1. Documented integrations include PHPUnit, an in-process headless API, framework presets and SARIF upload to GitHub Code Scanning. Installation is available through Composer as a development dependency or global package, or from source. Requirements are PHP 8.4+, ext-dom and ext-mbstring, with zero Composer runtime dependencies. Advanced engines are described as research-grade and may produce more false positives than the default set.