Free local spreadsheet converter
XLSX to CSV Converter — Free, Local, No Upload
The short answer: An .xlsx workbook stores data as a ZIP of XML parts that only spreadsheet apps read reliably. Converting XLSX to CSV flattens one sheet into a single plain-text table with a header row, so any tool — from a data pipeline to a text editor — can consume it. Choose the separator and optionally add a UTF-8 BOM (EF BB BF) at the start of the CSV. Check how the target application decodes the text.
How to convert XLSX to CSV
Convert XLSX to CSV now
The button opens the Excel Converter with XLSX → CSV preselected — it runs entirely in your browser and nothing is uploaded.
Open Excel ConverterLocal in your browser — nothing is uploaded
Open the converter
The button above opens the Excel Converter with the CSV output already selected.
Drop your XLSX file
Add the file (up to 50.0 MiB); .xlsx workbooks are read sheet by sheet and CSV files are parsed with explicit quoting rules.
Convert and download
Press Convert to process the workbook in a dedicated worker. When the result appears, press Download to save it. Cancel stops an in-progress run.
Conversion facts
- Input format
- XLSX
- Output format
- CSV
- Max file size
- 50.0 MiB
- Max dimensions
- Worksheet XML ≤ 200.0 MiB · Output ≤ 32.0 MiB · ≤ 256 columns
- Quality
- Value-level — formulas use cached values, styles dropped
- Processing
- Local in your browser — nothing is uploaded
XLSX
XLSX → CSV
What to watch
Only cell values survive: formulas contribute their cached value (never recalculated), styles, merged cells and column widths are dropped, and dates become ISO strings. One sheet converts per run — pick it from the sheet list. Input is capped at 50 MiB (the ZIP may expand to 200 MiB of worksheet XML) and output at 32 MiB; wider files should be split before converting.
Keep converting
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The tool behind this page
Excel ConverterConvert .xlsx workbooks to CSV or JSON, or CSV back to .xlsx, entirely in the browser — values only, with an optional UTF-8 BOM marker (EF BB BF) for CSV. Check decoding in your target app. Inputs up to 50 MiB, outputs up to 32 MiB.
Not sure which tool fits the job?
Structured Data ConverterCSV ⇄ JSON already lives there — this pair page deliberately does not duplicate it.