Choose csv / tsv from your device or use the available text controls.
Files stay on your device
CSV to XLSX
Create an XLSX workbook from CSV while preserving text, leading zeros and long identifiers.
Private browser workspaceInput: CSV / TSV → Output: XLSX
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Your file never leaves this browser
Processing happens locally using browser APIs and on-device code. Closing this tab clears the working data.
How it works01 02 03
Done in three simple steps
Choose the available options and process the input locally.
Review the result, then download it to your device.
Frequently asked questions
Why are numbers imported as text?+
Text storage preserves identifiers, dates and long numbers exactly without guessing. You can deliberately change cell types in Excel or another spreadsheet application.
Are my files uploaded?+
No. Processing happens on this device. The tool may download its own code, but source files and output are not sent to a processing server.