xlsm

xlsm is the file extension used by Microsoft Excel for macro-enabled workbooks. These files store spreadsheet data along with Visual Basic for Applications (VBA) code that automates tasks and adds custom functionality.

xlsm files are based on the Office Open XML format introduced with Excel 2007. They are zip archives containing multiple XML files and, for macro-enabled workbooks, a binary VBA project component named vbaProject.bin.

Typical use includes automating repetitive tasks, creating templates, building dashboards, and implementing custom functions. The presence of VBA code means macros in xlsm files can be executed within Excel; however, not all macro code is portable to other programs, and macros may rely on Windows-specific APIs.

Compatibility: Excel 2007 and later can open and save xlsm files. Older Excel versions (pre-2007) require compatibility packs and cannot natively open xlsm. Other applications may open xlsm with limited support for macros. Some non-Microsoft programs can open xlsm but macro execution is often not supported or is limited.

Security: because macros can contain malware, Excel uses macro security settings to disable, prompt, or enable macros. Macros can be digitally signed. Users should only enable macros from trusted sources.