🔤 Base91 Encoder/Decoder

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💡 Examples:"Hello World", binary data, JSON, or any text 💡 Examples: >OwJh>}AQ;r@@Y?F, fPNKd, or any Base91 encoded string
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vs Base64:

                    

                        Base91:  bytes | Base64:  bytes | 
                        
                             
                             bytes 
                            (%)
                        
                    

                

            

        


        
        

            

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                Showing unique characters used in Base91 encoding
            

        

    







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To Encode: Enter any text or binary data to convert to Base91 format

        
To Decode: Enter Base91 encoded text to convert back to original data

        
Input Formats: Plain text (UTF-8), hexadecimal, or binary strings

        
Advantages: More efficient than Base64 with shorter output and no padding required

    






    
        

        

            
ℹ️ About Base91 Encoder/Decoder

            

                

    Base91, often styled basE91, is a binary-to-text encoding for representing arbitrary
    bytes as printable ASCII. It serves the same kind of transport role as Base64 or uuencode, but uses a larger alphabet
    so the encoded text is usually shorter. Base91 is encoding, not encryption or compression: anyone with a compatible
    decoder can recover the original bytes.




    Common use cases:



    
    
  • Convert binary, UTF-8 text, hex, or bit strings into compact text for logs, terminals, email, or configuration values.
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  • Reduce the size overhead of text-safe binary payloads when Base64 is acceptable but not compact enough.
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  • Round-trip small binary samples while debugging protocols, file formats, serialization code, or API payloads.
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  • Compare Base91 output size with Base64 using the live byte and overhead statistics.
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    Technical details: the original basE91 algorithm keeps a bit accumulator and emits two printable
    characters for each 13 or 14 bits of input data, depending on the current value. Because two Base91 digits can express
    91 x 91 values, the format can pack data more densely than Base64's fixed 6-bit characters. Base91 does not use
    = padding, and the output length depends on the exact input bytes.




    Alphabet and overhead: the reference basE91 project describes an advanced ASCII encoding with overhead
    up to about 23%, and sometimes lower, compared with the 33% expansion commonly associated with Base64. Base91
    implementations are not all interchangeable: the exact alphabet matters, and some libraries substitute or omit
    punctuation for JSON, shell, or string-literal safety.




    Examples: with this tool's current alphabet, Hello World! encodes to
    >OwJh>Io0Tv!8PE, and fPNKd decodes to test. For hexadecimal input,
    enter bytes such as 48656c6c6f and choose the Hexadecimal mode before encoding.




    Limitations and compatibility:



    
    
  • Base91 is less widely supported than Base64, so it is best for systems where both sides explicitly agree on Base91.
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  • Encoded output may contain punctuation that needs escaping in JSON strings, shell commands, HTML attributes, URLs, or SQL literals.
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  • Different Base91 alphabets or quote-safe variants can decode the same characters into different bytes.
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  • Decoded bytes are shown as text here; arbitrary binary data may not display cleanly if it is not valid UTF-8.
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    Privacy note: the interactive page processes text in your browser after the tool script loads. If you
    use the public API endpoint, the input is sent to the server for processing.




    References: see the original
    basE91 project
    and RFC 4648 for the standard
    Base64/base-encoding comparison point.


            

        

    

    
    
                                                                                                        

        
API Usage Example:

        
POST /api/tools/encoding-decoding/base91
Content-Type: application/json

{
    "text": "Hello World!",
    "operation": "encode",
    "format": "text"
}

    

            
            

    




                

            


            
            

                Ready