How to encode excel files to base64 without python base64.b64encode() or cli tools
- Step 1Upload the Excel file to encode — Drop the .xlsx. FileReader.readAsDataURL() starts encoding immediately.
- Step 2Copy the Base64 string — The encoded string is shown in the preview. Click Copy to Clipboard.
- Step 3Use in your API call or code — Paste into your JSON body, curl command, or Postman request — identical output to base64.b64encode().
Frequently asked questions
Is the output identical to Python's base64.b64encode()?+
Yes. Standard Base64 encoding is deterministic — the browser tool and Python produce the same output for the same input file.
What about the data URI prefix (data:application/...;base64,)?+
The tool shows both the full data URI and the raw Base64 string. Python's b64encode() produces only the raw string — copy that version for API use.
Does the browser have performance limits compared to Python?+
For files up to 50 MB (Pro tier), the browser FileReader is fast enough for interactive use. For batch-encoding many files, a Python script is more efficient.
Privacy first
Every JAD Excel tool runs entirely in your browser using SheetJS and ExcelJS. Your spreadsheets, formulas, and data never leave your device — verified by zero outbound network requests during processing.