Excel Command Line Utilities

Mar. 14, 2026

I am still not running Claude in dangerous mode. In the process of frantically approving things, I realized Claude keeps checking the content of spreadsheets by calling Python.

uv run --project ./my_project python -c "
   import openpyxl
   ...
   "

I am not yet at the stage where I let Claude write arbitrary Python scripts. I vibecoded some tools to do basic things with spreadsheets in a fast and predictable way. The constraints: compiled command line utilities, with limited side effects that I can trust Claude to use without my approval.

go-xldiff : when making changes to a spreadsheet, even when we track them with version control, it’s hard to tell what the changes were. This converts two sheets to csv, compares the cells, and returns a diff. Simple but effective when making small changes and the coding agent is always looking for what just changed.
xl-cli-tools : provides two commands. xlcat gives a snippet of sheets to the command line in markdown. xlset allows modifying specific cells in a spreadsheet.

I also had Claude write some skills to use them. I think it’s working.

xlcat — view	xlset — edit