Feature Request: Add support for Excel (.xlsx) and CSV file types

[DhruvParikh1]

Feature Request: Excel and CSV File Type Support

Summary

Add support for diffing Excel (.xlsx) and CSV (.csv) files in the differ tool.

Motivation

Many users work with tabular data stored in Excel spreadsheets and CSV files. Currently, differ does not support these file types, which means users cannot take advantage of the tool's diffing capabilities for their data files. Adding support for these formats would significantly broaden the tool's usefulness for data analysts, developers, and business users.

Proposed Behavior

CSV files (.csv):

• Parse CSV files and display diffs row-by-row and cell-by-cell
• Highlight added, removed, and modified rows/cells
• Handle common CSV variants (comma, semicolon, tab-delimited)

Excel files (.xlsx, .xls):

• Parse Excel files and support diffing sheet contents
• Display cell-level diffs with clear visual indicators
• Optionally support multi-sheet diffing

Expected Benefits

• Enables diffing of tabular data without manual conversion
• Improves usability for data-heavy workflows
• Brings differ closer to feature parity with other popular diff tools

Alternatives Considered

Users currently need to manually export spreadsheets to plain text or use external tools before diffing, which is cumbersome and error-prone.

Additional Context

This is a commonly requested feature for diff tools. Libraries such as SheetJS (xlsx) can parse both .xlsx and .csv formats and may simplify implementation.