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Excel to Base64 Encoder

Convert an Excel .xlsx workbook to a Base64 string. Runs entirely in your browser.

Excel to Base64 encodes XLSX or XLS spreadsheets into a Base64 string. ConvertDa's free Excel to Base64 tool runs in your browser — useful for embedding spreadsheets in JSON requests, email attachments, or data URIs in web apps.

How to excel → base64

  1. 1

    Drop your spreadsheet file in.

  2. 2

    Copy or download the Base64 string.

Frequently asked questions

Does it work with CSV files?▾

Yes — CSV, XLS, and XLSX are all supported.

Which MIME type is added with the data URI prefix?▾

XLSX uses 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'. XLS uses 'application/vnd.ms-excel'. Both are detected automatically.

Will formulas survive Base64 encoding?▾

Yes. Encoding is a byte-level transformation that doesn't touch the file's contents — formulas, formatting, and charts are preserved when decoded back.

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