Base32 Encoder & Decoder

Base32 writes binary data using only 32 characters — the capital letters A–Z and the digits 2–7 — so the result survives case-insensitive systems, file names and being read aloud. It is the format of the secret keys behind authenticator apps (TOTP two-factor codes) and is defined in RFC 4648. This tool encodes UTF-8 text or raw hex bytes, and decodes Base32 back to text and bytes.

How to use this tool

1. Choose Encode or Decode.
2. Paste your text — or, for encoding, switch "Input is" to hex to encode raw bytes.
3. Keep the standard alphabet unless your system says Base32hex (used, for example, in DNSSEC NSEC3 records).
4. Untick padding if the receiving system wants no trailing = signs (most TOTP apps accept both).

Formula

Each 5 bytes (40 bits) are split into eight 5-bit groups; each group (0–31) selects one alphabet character.

A final partial group is filled with zero bits, and with padding on, = signs bring the length up to a multiple of 8. The output is 8/5 of the input size — 60% larger — compared with about 33% for Base64.

Example

Encoding the text "foobar" (6 bytes) gives MZXW6YTBOI======, the official test vector from RFC 4648. The first 5 bytes produce MZXW6YTB, the sixth byte "r" produces OI, and six = signs pad the result to 16 characters. With the Base32hex alphabet the same input becomes CPNMUOJ1E8======.