Spreadsheet

This is a comprehensive toolkit for working with Excel and CSV files through Claude, covering everything from quick data analysis to full investment banking models. It uses openpyxl for preserving formatting and formulas in .xlsx files, pandas for analysis, and includes specific conventions like color coding inputs versus formulas and handling financial layouts with proper borders and number formatting. The workflow includes optional PDF rendering for visual checks if you have LibreOffice installed. What stands out is the attention to real world details: it knows formulas won't evaluate in openpyxl, tells you to cite sources in cell comments for financial models, and includes IB-specific formatting rules like red parentheses for negatives and merged dark headers. If you're building spreadsheets programmatically and need them to look professional rather than obviously generated, this covers the details most code examples skip.