Base91 Encoder / Decoder
Compact binary-to-text encoding — ~23% overhead vs Base64's ~33%.
Direction
Drop a binary file to encodeEncodes raw bytes to Base91 — images, binaries, anything.
What is Base91?
Base91 is a binary-to-text encoding scheme that uses 91 printable ASCII characters. It achieves approximately 23% overhead relative to the binary input, compared to Base64's 33% overhead, making it more compact for arbitrary binary data. Every group of 13 or 14 bits maps to two characters from the 91-character alphabet — so Base91-encoded output is meaningfully shorter than Base64 for the same input. This makes it useful in situations where minimising encoded size matters, such as embedding binary data in source code, transmitting payloads over character-limited channels, or storing compact checksums.
Private & free — this tool runs entirely in your browser.
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