Research Local Plagiarism checker

This is a quick easy project. I require some research a local plagiarism checker to check for similarities across local files. I simply need an easy to use content checker that will check. We have a local file repository that consists of years of data and research that we sometimes reuse. However we need to check that in the new content we haven't accidentally used something we previously wrote. We are looking for someone to research and recommend a software that scans our local files. thanks,