Base32 Encoder and Decoder

About Base32 encoder and decoder

Base32 represents bytes using only 32 characters, which makes it safe for case-insensitive systems and easy to read aloud or type by hand. This page encodes text to Base32 and decodes it back following RFC 4648, with a padding switch and a choice between the standard alphabet and the Base32hex alphabet. Output updates as you type.

How to use it

1. Choose Encode or Decode under Mode.
2. Under Alphabet, pick Standard (A-Z, 2-7) or Base32hex (0-9, A-V).
3. Type or paste into the input box. Results appear immediately in the output box below.
4. When encoding, use the Add = padding switch to include or drop the trailing equals signs.
5. Use Use as input to swap direction with the output as the new input, or Copy to take the result.

The RFC 4648 sample string

foobar

Standard MZXW6YTBOI====== and Base32hex CPNMUOJ1E8======. With padding off the standard result is MZXW6YTBOI.

When to use it

• Reading or writing the shared secret that a two-factor authentication app expects, which is Base32.
• Encoding identifiers for systems that ignore letter case, such as file names on some file systems.
• Decoding a Base32 string from a log or config to see what text it holds.
• Producing sortable encoded keys with the Base32hex alphabet, which preserves byte order.

Questions about Base32 encoder and decoder

Why does Base32 avoid the digits 0, 1, 8 and 9?

The standard alphabet uses A to Z and 2 to 7. Leaving out 0, 1, 8 and 9 removes look-alikes such as zero and the letter O, or one and the letter I, when a value is copied by hand or dictated.

How much bigger is Base32 than the original data?

Each 5 bytes become 8 characters, so the output is about 60 percent larger than the input before padding. That is more than Base64's 33 percent, the price paid for a safer alphabet.

What does the decoder accept?

It ignores whitespace, treats lowercase as uppercase, and does not require padding. It rejects characters outside the chosen alphabet, equals signs in the middle, and lengths that cannot come from whole bytes.

Why do I see a message about UTF-8 when decoding?

The tool shows the decoded bytes as text. If the Base32 holds binary data such as a raw key, those bytes are not valid UTF-8, so no text can be displayed even though the encoding itself was correct.

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