Base32 Decoder Developer
Decode Base32 back to text, ignoring padding, spaces and case.
Base32 Decoder is a free online tool that decode Base32 back to text, ignoring padding, spaces and case. It runs entirely in your web browser using plain JavaScript, so files are processed on your own device and never uploaded to a server. There is no sign-up, no file size limit imposed by the site, no watermark and no paid tier.
- Price
- Free — no account, no quota, no watermark
- Category
- Developer
- Where it runs
- In your browser, on your device
- Files uploaded
- None
- Technology
- plain JavaScript
- Settings
- None — it just works
- Works offline
- Yes, after the first visit
About Base32 Decoder
Decoding is deliberately forgiving about everything the standard does not treat as data. Padding, spaces, hyphens and lowercase are all normalized away before decoding, because Base32 in the wild arrives formatted for humans — TOTP secrets are routinely shown in groups of four, and a secret copied from a screen brings its spaces along. Anything left that is not in the A–Z and 2–7 alphabet is reported by name rather than silently skipped.
How to use it
- Paste the text you want to run through base32 decoder.
- There is nothing to configure — the result updates as you type.
Under the hood
| Runs on | plain JavaScript — runs the whole thing |
Questions
Why does my secret contain 0 or 1?
Then it is not Base32. The alphabet deliberately excludes 0, 1 and 8 because they are easily confused with O, I and B. A string containing them is probably Base64, hexadecimal, or has been transcribed with an error.
Can I decode a TOTP secret with this?
You can decode it to its raw bytes, which is what the algorithm actually uses. Generating codes needs the HMAC step and the current time as well — this shows you what is inside the secret, not what the app would display.
Does it accept lowercase?
Yes. Base32 is case-insensitive by design, so input is uppercased before decoding. That is the whole reason the encoding exists.