Base 64 Decoder

Quickly decode your Base64 encoded strings back into plain text or binary data with our free online Base64 Decoder. This tool is essential for developers needing to read data that has been encoded for safe transmission over text-based protocols. For your privacy, all processing happens right in your browser. Your data is never sent to us or logged. (looking for encoding?)

What is Base64 Decoding?

Base64 decoding is the process of converting a string of ASCII characters back into its original binary or text format. It reverses the encoding scheme that represents data in a radix-64 representation.

How Base64 Decoding Works

When you decode Base64, the process takes groups of four characters from the encoded string and converts them back into the original three bytes of data. This is the inverse of the encoding process used to ensure data integrity during transport over systems that only support text.

The decoder looks at the Base64 index table to map each character back to its 6-bit value. These bits are then concatenated and split into 8-bit bytes. If the encoded string ends with = or ==, these are padding characters used to ensure the encoded data fits the required length, and they are discarded during the decoding process.

Base64 Index Table (RFC 4648)