From Knight Consulting:
Excel Overlay compares two Excel spreadsheets and displays the differences using a new and intuitive approach. It assumes both spreadsheets are similar to each other and once "overlaid" onto one another, the differences become plainly apparent and easily corrected. This tool was designed for speed and is the fastest Excel spreadsheet comparison tool on the market today. Most tools of this nature are both slow and non-intuitive. They spit out a vast amount of discrepancies in either two side by side grids or hard to reconcile summary spreadsheets. Excel overlay allows you to make corrections right within the tool itself after which it will build you a brand new, corrected spreadsheet. The new spreadsheet will be the combination of the two you were comparing and any corrections or changes you made within this tool. Version 9.0.1 added support for .xlsx extension.
What's new in this version:
Version 9.0.1 added support for .xlsx extension.