jscpd

Why we included this project

Codebases accumulate duplicate blocks faster than most teams notice, and jscpd exists to catch them. It scans source files in over 200 formats using the Rabin-Karp algorithm, so you get a precise list of copy-pasted regions instead of a vague quality score. The project ships a TypeScript engine and a Rust rewrite that runs 24 to 37 times faster, which keeps it cheap enough to run in CI or as a pre-commit hook. It also fits AI-assisted workflows: an MCP server and agent skills let coding assistants run duplication checks themselves, and a token-efficient reporter keeps findings compact enough to fit an LLM context window. For teams enforcing DRY discipline or adding quality gates around AI-generated code, this is a concrete, scriptable tool you can wire into your pipeline.