Spreadsheet Format Converter

This tool is a server-side conversion engine that accepts a source Excel workbook in XLSX and outputs an XLS file. It is designed for data teams, IT admins, and analysts who must preserve data integrity while downgrading format compatibility. It processes the workbook's sheets, values, and basic formatting; it attempts to preserve formulas by translating modern functions to the closest equivalent in older Excel. It does not execute macros if not supported, and macros in XLSX are not present.
Core logic includes input validation, feature compatibility checks, and a deterministic mapping workflow. Requirements: input file must be XLSX or XLS; optional: user may request batch mode or preserve formatting; The engine checks for unsupported features like dynamic arrays, certain named ranges, or new data types and flags them in a concise report. It then outputs a new workbook in XLS, truncates features that are not supported, and produces a metadata file with a compatibility report.
Audience and differentiators: data engineers needing legacy support; QA teams verifying downgrades; bigger organizations requiring automation. The key differentiators are explicit compatibility reporting, batch processing, and safe fallback for unsupported content. The tool focuses on preserving data content while noting limitations; It adheres to common Excel date systems (1900 or 1904) and locale-aware number formatting.