Document Xlsx

This is a solid reference for creating, reading, and manipulating Excel files programmatically. It covers the main libraries (openpyxl, XlsxWriter, ExcelJS, pandas) and walks through common tasks like formatting cells, writing formulas, adding charts, and conditional formatting. The security and accessibility callouts are worth paying attention to, especially the warnings about formula injection and treating untrusted workbooks as hostile. The decision tree at the end helps you pick the right tool for the job. If you're automating reports, building financial models, or processing spreadsheet data without opening Excel, this gives you the patterns and guardrails you need. The formulas are written by the library but calculated by Excel when opened, so plan accordingly if you need server-side computed values.