Convert CSV to XLSB

Convert CSV files to XLSB locally, completely free and with maximum privacy.

Drag and drop your files here

or click to browse local files (large files supported, limited only by browser RAM)

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How to convert CSV to XLSB

Drop your .csv files above, or click Upload Files. You can add many files at once.
XLSB is already selected as the output. Open the settings (gear icon) to fine-tune the result.
Click Convert All. SheetJS runs inside your browser through WebAssembly; nothing is uploaded.
Download your .xlsb files as soon as each one finishes.

What to know about CSV to XLSB conversion

Numbers and dates are detected automatically, and accented characters are kept intact (UTF-8).
XLSB is best for very large Excel workbooks that must open fast, and opens in Excel and LibreOffice.

CSV vs XLSB

Feature	CSV (Comma-Separated Values)	XLSB (Excel Binary Workbook)
Multiple sheets	No	Yes
Formulas and formatting	No	Yes
Best for	importing data into databases, CRMs and apps	very large Excel workbooks that must open fast
Opens in	any spreadsheet, database or text editor	Excel and LibreOffice

CSV (Comma-Separated Values): A plain-text tabular format where each line is a row and values are separated by commas.

XLSB (Excel Binary Workbook): A binary Excel format that loads and saves large workbooks faster than XLSX.

Conversion options

Active sheet only or all sheets
Custom output file name

Frequently asked questions

Is it safe to convert CSV to XLSB here?

Yes. Your files are processed entirely on your own device by WebAssembly code running in the browser. They are never uploaded, so nobody else can see them, and the converter keeps working even if your connection drops after the page loads.

Is there a file size limit?

There is no server-side limit. The only limit is the memory available to your browser, typically 1.5–4 GB on desktop computers.

Can I convert several CSV files at once?

Yes. Add as many files as you like; they are converted in parallel according to your device's CPU cores, and you can apply the same settings to all of them.

Related conversions

Need the opposite? Convert XLSB to CSV.

Convert CSV to other formats

Convert other formats to XLSB

See every CSV converter and XLSB converter, or browse the full converter directory.