How to Base64 Encode & Decode in Excel (Offline)
Excel has no Base64 or URL function, so people paste sensitive strings into random websites to convert them. Encode or decode a whole column — Base64, URL, hex, or HTML — entirely on your own device.
Last updated: August 2026
| Text | Base64 | |
|---|---|---|
| hello | → | aGVsbG8= (encode) |
| aGVsbG8= | → | hello (decode, same tool) |
Why there's no built-in way
Excel ships no BASE64, URL-encode, or hex function, and there's no clean formula for any of them. So the common workaround is to paste the strings into an online encoder — which means handing sensitive data to a website you don't control. For tokens, IDs, or anything private, that's exactly what you don't want.
The 1-click way — Tellsheet's Developer Encoders
Select the column and run Developer Encoders. Choose Base64, URL-encoding, hex, or HTML-escaping, pick the direction — encode or decode — and Tellsheet transforms every cell entirely on your device. It's the offline, privacy-safe alternative to web encoders, so nothing is ever uploaded. Pairs with Clean HTML and Anonymize Data.
Frequently asked questions
Does Excel have a Base64 function?
No — there's no built-in Base64 or URL-encode function. Developer Encoders adds all of them to a column without formulas.
Is my data sent anywhere?
No — everything runs on your device. It's the privacy-safe alternative to pasting strings into random web encoders.
Which formats are supported?
Base64, URL-encoding, hex, and HTML-escaping — each in both directions.
Can it decode too?
Yes — every format works both ways. Pick the direction and it encodes or decodes the column.
Related Excel guides
Encode a column without leaving Excel
Developer Encoders does Base64, URL, hex, and HTML both ways — entirely on your device, nothing uploaded.
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