Start from a deliberate copy
An XLSB workbook can contain much more than a grid of values. It may combine saved calculations, charts, hidden support sheets and external data. Before conversion, keep an untouched copy and decide whether the recipient needs the data or a fully functioning Excel model. This product serves the data handoff, so the new workbook has a narrower purpose.
Choose the source file and inspect all sheets first. Hidden sheets can contain lookup tables or sensitive notes; their existence does not mean they should automatically be shared. Use visible-only selection or exact names after reviewing the preview and original visibility flags. The exported report records which sheets were included.
Compare the cells that matter
Download the values-only XLSX and inspect representative identifiers, dates, Boolean values, error cells and formula results. The source formula can be present while its last saved result is missing or out of date. The tool does not open Excel, recalculate a model or contact an external workbook to obtain a newer answer.
The CSV package contains one numbered file per selected sheet and a manifest mapping filenames to original sheet names. A CSV is useful for another data pipeline, but it has no workbook-level date system or cell types. Import identifiers explicitly as text when the receiving application would otherwise remove leading zeros.
Retain the evidence of the handoff
Keep the JSON report next to the extracted files. It records readable source cell types, formula text and cache values, the date system, visibility decisions and detected omitted parts. These details make a later discrepancy easier to investigate than a converter that only produces a new extension.
If the recipient needs pivot refresh, a working chart or the exact print layout, return to the original workbook in a compatible spreadsheet application. A successful data export does not certify that every XLSB feature has been reproduced. Test the important downstream task before replacing an established workflow.