Base91 Encoder / Decoder

Encode binary data as basE91 — a denser alternative to base64 (~13% smaller output for the same input). Uses 91 printable ASCII characters (everything except backslash, single quote, and double quote, plus space). Useful for protocols that need text-safe encoding but want to save bytes over base64.

How to use the Base91 Encoder / Decoder

Encode: paste text, get basE91-encoded output. Decode: paste basE91 string, get the original. Whitespace in encoded input is ignored on decode.

About Base91 Encoder / Decoder

basE91 was created by Joachim Henke as an answer to "what if base64 used more characters?". By using 91 characters from the 7-bit ASCII printable range, basE91 packs each pair of input bytes into roughly 14 bits of output (the encoder uses variable-length blocks). The resulting output is ~13% smaller than base64 for the same input, while remaining safe for any 7-bit text channel.