Ascii85 / Base85: Encode, Decode and Translate Text Online Ascii is a form of binary-to-text encoding developed by Paul E. Rutter. This decoder uses five ASCII charaters to represent four bytes of binary data. This makes the encoded message 1/4 larger than the original data. ASCII is more efficient than base64 which uses four characters to represent three bytes of data. If this tool was helpful, tweet it or share it.