Base32 Encoder / Decoder

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base32 rfc 4648 alphabet

Base32 per RFC 4648, alphabet, padding and variants

RFC 4648 defines three encoding schemes: Base64 (§4), Base32 (§6) and Base32hex (§7). Each Base32 variant has specific uses. This page documents the differences and helps you choose the correct variant.

Base32 §6 vs Base32hex §7

Base32 §6 uses A-Z and 2-7, no 0/O/l/1/8. This is the standard for TOTP, Tor, human identifiers. Base32hex §7 uses 0-9 and A-V, it sorts lexicographically the same as the binary values, making it useful for NSEC3 (DNSSEC) and systems needing consistent ordering.

Variant comparison

Base32 §6 (A-Z 2-7)

Input: test
Expected output: ORSXG5A=

Standard for 2FA and .onion addresses.

Base32hex §7 (0-9 A-V)

Input: test
Expected output: EHI6GU0=

For DNSSEC and lexicographic ordering.

Full tool FAQ

Which Base32 variant should I use?

If the other side says RFC 4648 without qualifying, it means the A-Z2-7 alphabet with padding. Use base32hex when the alphabetical order of the encoded text has to follow the numeric order of the data, which is the case for NSEC3 in DNSSEC. Use Crockford when the code will be read and typed by people and you want to catch errors on the spot with the check symbol. Use z-base-32 when the value will be spoken aloud. Picking the wrong one corrupts nothing, but the other side will not be able to decode it.

Why does Crockford turn O into 0 and I into 1?

What is the Crockford check symbol?

Is my 2FA secret Base32?

How long should a TOTP key be?

What does the non-canonical trailing bits warning mean?

What is the overhead of Base32?

Does Base32 protect my data?

Frequently asked questions

Why does standard Base32 not use 0, 1, 8 and 9?

Base32 §6 uses digits 2-7 (not 0, 1, 8, 9) because: 0 and O are ambiguous, 1 and l are ambiguous. 8 and 9 were excluded to reserve space for 2-7 after the 26 letters, keeping the total at 32. Base32hex §7 uses 0-9 and A-V because the goal is lexicographic ordering, not human typing.

Does this page replace official or professional review?

No. It helps explain the scenario and use the tool more safely, but real decisions should consider official sources, full context and qualified guidance when needed.

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