A Base91 Encoder transforms binary data into a text representation using 91 printable ASCII characters. It processes input by dividing it into 13-bit groups, each mapped to two characters from the Base91 alphabet. This method is more efficient than Base64, offering up to 58% less overhead, making it useful for transmitting data over text-based media. Common applications include embedding binary data in text files and transferring data over protocols that handle text.

A Base91 Decoder reverses this process, converting Base91-encoded text back into its original binary form. It interprets each pair of encoded characters, maps them back to their 13-bit binary representation, and reconstructs the original data. This decoding is essential for retrieving original content from Base91-encoded strings, ensuring data integrity during transmission. It's important to note that Base91 encoding is not a form of encryption and does not provide data confidentiality.