Excel to Base64 Converter Online
Encode XLSX, XLS, XLSM and CSV files as Base64 text, ready for APIs, JSON and email. 100% private, client-side encoding with zero server uploads.
How to Convert Excel to Base64
Drop or browse for an .xlsx, .xls, .xlsm, .xlsb or .csv file.
Optionally add a data URL prefix or split the output into 76-character lines.
Copy the Base64 text or save it as a .txt file.
How Excel to Base64 Encoding Works
Base64 turns the binary bytes of a spreadsheet into plain text. That makes it easy to send a workbook inside a JSON body, an XML field or an email.
Everything runs in your browser. To turn the text back into a file, use the Base64 to Excel Converter. For PDFs, see the Base64 to PDF Converter.
When to Use Each Option
- Data URL prefix: adds
data:...;base64,for use in HTML, CSS or browser code. - 76-character lines: the MIME format used by some email systems and older APIs.
- Plain output: best for most JSON APIs. An .xlsx file usually starts with
UEsDB.
Need to inspect the raw bytes instead? Try the Text to Hex Converter.
Frequently Asked Questions
Is my Excel file uploaded to any server?
No. The file is read and encoded inside your browser. Nothing is sent to a server.
Which file types are supported?
XLSX, XLS, XLSM, XLSB and CSV, up to 30 MB.
Why is the Base64 text larger than my file?
Base64 adds roughly one third to the size because each 3 bytes become 4 text characters.
How do I turn the Base64 back into Excel?
Paste it into the Base64 to Excel Converter. It restores the original workbook.