No, Delimit does not work with native Excel files (*.xlsx), Delimit works with text files such as CSV files (*.csv), TAB delimited files (*.tab) and fixed column width files (*.txt), to name a few. People often confuse CSV files as Excel files but they are really just text files. So if you work with CSV files then you will be able to open and save them in both Delimit and Excel. Note that Delimit can handle much larger CSV files; up to 2 billion rows and 2 million columns large.