Base91 Encode & Decode
A very compact encoding using 91 printable characters. This tool does both encode and decode on one page — just pick a mode, paste your text, and click. Everything runs on your device, nothing is sent to a server.
Everything runs in your browser. Your data is never sent to our servers.
Example
Example Input
Hello
Example Output
x;bD6#
How to Use
- 1Choose Encode or Decode mode at the top.
- 2Type or paste your text into the Input field.
- 3Click the button (or press Ctrl+Enter) to process. The result appears in the Output field.
- 4Click Copy to copy the result, or "Swap input/output" to quickly reverse the operation.
About Base91
Base91 encodes data using 91 printable ASCII characters, producing output more compact than both Base64 and Base85. The more symbols per character, the fewer characters needed.
How it works: unlike fixed-block base-n schemes, Base91 packs bits variably into character pairs, so its efficiency approaches the theoretical limit for printable characters.
Base91 is useful when output size really matters and you only need printable ASCII. The trade-off: it is less common/standard than Base64.
FAQ
Can this Base91 tool both encode and decode?
Yes. This is a single page with a toggle — use Encode mode to transform text, and Decode mode to reverse it. No need for two separate pages.
Is my data sent to a server?
No. Base91 is processed entirely in your browser. The text you enter never leaves your device.