Jscpd

This is a copy-paste detector that scans 220+ languages and shows you where code is duplicated across your codebase. The standout feature is the AI reporter mode, which outputs a compact, token-efficient format that's actually readable for agents instead of drowning you in verbose reports. You can set thresholds to fail builds if duplication crosses a line, ignore patterns for node_modules or generated code, and tune sensitivity with minimum lines or tokens. It's practical for pre-commit checks or CI pipelines when you want to catch duplicate code before it spreads. The tool also pairs with a separate dry-refactoring skill if you need help actually removing the duplication once you've found it.