What is .GNM file extension?
Spreadsheet file created by Gnumeric, an open source spreadsheet application developed by the GNOME Project; stores formatting information, charts, and other data used in the spreadsheet; similar to Excel spreadsheet files (.XLSX), both containing data stored in the XML format; compressed using GZIP compression.
NOTE: GNM files are also commonly saved with the .GNUMERIC file extension.
You can see a list of software programs here on easyfileopener.org that can open this file type so that you don’t need to search for it on the web. You can then open your file with this extension using a software listed below.