File Substring Replacement Utility (FSRU) performs multiple text search and replace operations on multiple files. Designed specifically for computer programmers working on large projects with many source code files, however any type of file can be used, including HTML. Search and replace operations can also be performed on filenames (mass renaming). A detailed log is kept of every substring that is found and replaced. Case-insensitive, whole-word, wildcards, and command line searches are supported. Windows 98, NT4, 2000, ME, XP, 2003, and Vista.