In short
This tool tidies up an Excel, OpenDocument or CSV table, typically a software export or a list filled in by several people. It removes duplicate rows, empty rows and columns and spaces at the start and end of cells, and collapses multiple spaces and line breaks. Two rows that are identical across all their columns are duplicates: the first one is kept, and the header row, if you indicate one, is never removed. A preview shows the result before saving. The tool cleans one sheet at a time: the workbook's other sheets stay intact. A CSV stays a CSV, an .ods stays an .ods, and other workbooks are saved as .xlsx. The clean-up happens in your browser.