What characters are valid in Base32?

Standard RFC 4648 Base32 uses the uppercase letters A through Z and the digits 2 through 7. Padding is done with the = character. This tool accepts lowercase input and normalizes it automatically.

Why do I get an error about invalid characters?

Characters outside the Base32 alphabet (e.g. 0, 1, 8, 9, or symbols) are not allowed. Make sure you are not confusing Base32 with Base64, which uses a different character set.

Does this tool support Base32Hex?

This tool decodes standard RFC 4648 Base32 only. Base32Hex uses a different alphabet (0-9 then A-V) and is a separate variant not handled here.

Is my data sent to a server?

No. All decoding happens entirely in your browser using JavaScript. No data is transmitted to any server.

What if the decoded bytes are not valid UTF-8?

The tool will attempt to display the result as text. If the decoded bytes contain non-printable characters, a warning is shown and you can view the raw hex representation instead.

Base32 Decoder

Name: Base32 Decoder
Availability: InStock
Author: Nham Vu

Paste a Base32-encoded string and instantly decode it back to plain text.

Base32 Encoded Input

Options

Also show hex output

Decoded Output

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Summary

Paste a Base32-encoded string and instantly decode it back to plain text.

How it works

Paste or type your Base32-encoded string into the input box.
The decoder strips whitespace and normalizes the string automatically.
It validates that all characters are legal Base32 characters (A-Z and 2-7).
The decoded bytes are interpreted as UTF-8 text and displayed in the output.
Use the Copy button to copy the decoded result to your clipboard.

Use cases

Decode TOTP/2FA secret keys to inspect their raw byte values.
Decode Base32-encoded identifiers used in APIs or databases.
Verify Base32 output produced by an encoder during development.
Decode encoded file names or tokens in security tools.
Inspect Base32 payloads in email or network protocols.
Debug authentication libraries that store secrets in Base32.

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu