Gnumeric Spreadsheet (.gnm)
The GNM file extension, short for Gnumeric, is used by the Gnumeric spreadsheet application, part of the GNOME Desktop Software. It stores spreadsheet data in rows and columns, supports charts, and other functionalities. GNM files are compressed XML files, similar to XLSX, and can be decompressed using standard utilities like WinZIP. Gnumeric aims to provide an open-source alternative to Microsoft Excel.