Convert XLSX to CSV
Turn an Excel .xlsx workbook into plain CSV — right in your browser. Reads the workbook's real ZIP+XML structure, lets you pick which sheet if there's more than one, and downloads a clean, properly-escaped CSV. Nothing is uploaded.
Convert an XLSX File to CSV
Drop an .xlsx file below. It's read using the same from-scratch ZIP and XML parser as our XLSX viewer tool — every sheet is decoded right in your browser, previewed, and ready to convert and download as CSV.
🔒 Nothing is uploaded — your file never leaves this deviceOn this page
How the XLSX-to-CSV conversion works
An .xlsx file is a ZIP archive of XML — this tool reads it the same way a spreadsheet program does, rather than treating it as an opaque binary blob:
- ZIP central directory reader — locates and reads every entry inside the workbook archive from scratch, decompressing deflated parts with the browser's native
DecompressionStream. - SpreadsheetML parsing — reads
xl/workbook.xmlfor the sheet list, the shared-strings table for text values, and each worksheet's cell grid, resolving cell types (string, number, boolean, inline string, formula result) the same way Excel does. - CSV writing — every cell value is escaped per RFC 4180 (quoting values that contain a comma, quote or line break) before being written to the output.
Why convert XLSX to CSV
CSV is the universal format almost every program, database and script can import without needing to understand Excel's binary/ZIP structure at all. Converting an .xlsx report or export to CSV is usually the first step before loading it into a database, a script, or any tool that only speaks plain delimited text.
Edge cases this tool handles
Multiple sheets
Each sheet is decoded separately — pick the one you need from the tabs above the preview and convert it on its own.
Formula cells
Converted using the last-calculated value stored in the file (the same number Excel displays), since CSV has no way to represent a live formula.
Shared strings and inline strings
Excel stores repeated text values in a shared table for efficiency, and one-off text inline — both are resolved correctly to the actual text.
Very large sheets
Extremely large sheets are read up to a generous row/column cap to keep the browser responsive; if you hit it, splitting the source workbook is the practical workaround.
Frequently asked questions
Does converting XLSX to CSV upload my file anywhere?
No. The workbook is read and converted entirely inside your browser — a from-scratch ZIP and XML reader, no library, no server. The file's contents never leave your device.
What happens to formulas when converting to CSV?
Formula cells are converted using their last-calculated value, the same value Excel itself stores and displays — not the formula text. CSV has no concept of formulas, so this is the only way to represent a calculated cell in the output.
What happens to a workbook with multiple sheets?
CSV can only represent one flat table, so with a multi-sheet workbook you pick which sheet to convert and download; each sheet has to be converted and downloaded separately, since there's no single CSV that could hold all of them at once.
Does formatting, like cell colors or column widths, carry over?
No — CSV is plain text with no concept of formatting, so only the actual cell values are preserved. This is inherent to the CSV format, not a limitation of this specific tool.
Last updated September 23, 2026.