13 Best Duplicate Code Checker Tools in 2026

Code duplication is the silent tax on every codebase I have worked on codebases where fixing a single bug required changing the same logic in seven different files. Not because the architecture demanded it - because someone copy-pasted a function years ago, and then someone else copy-pasted the copy, and then the copies diverged slightly, and nobody knew which version was canonical anymore. That is the real cost of code duplication. It is not just wasted disk space or inflated line counts. It is