Decode Base64 Online

A Base64 online decode tool is a web-based utility that allows you to easily decode base64 string to plain text

What is Base64?

Base64 is a binary-to-text encoding scheme that represents binary data in an ASCII string format. It is commonly used for transmitting binary data over channels that only allow text, such as email attachments or HTTP requests. Base64 converts each 3 bytes of data into 4 bytes of ASCII text, allowing the data to be transmitted as text characters.

Base64 uses a set of 64 characters (hence the name) that includes the 26 uppercase and lowercase letters of the English alphabet, the 10 digits, and the symbols "+" and "/". The "=" symbol is also used as a padding character to ensure that the length of the encoded string is a multiple of 4 characters.

To encode data in Base64, each group of 3 bytes of data is split into 4 groups of 6 bits, which are then represented by the corresponding Base64 character. If the input data is not a multiple of 3 bytes, padding is added at the end to ensure that the final group of 6 bits is fully represented by a Base64 character.

To decode Base64-encoded data, the process is simply reversed, with each group of 4 Base64 characters being converted back into 3 bytes of data.
To learn more about Base64, please visit Base64 Wikipedia page.

How Base64 Decoding Works?

Let's say we have the base64 encoded string "SGVsbG8gV29ybGQh". To decode this string, we would first convert it to its 6 bit values corresponding to their ASCII values, which are:
00110100101 000011100001100011 00010100000010001110000 0000000100011000 0001000011

Next, we are going to split the binary string into groups of 8 bits (1 byte). If the length of the string is not a multiple of 8, padding with 0s is added to the end.
00110100 10100001 11000011 00011000 10100000 00010001 11000000 00010000 11000001 00001000 01100000 01000011 00000000 00000000

Convert each 8-bit binary value to its decimal equivalent and then map it to the corresponding ASCII character.
Hello World!

So the Base64-encoded string SGVsbG8gV29ybGQh is an representation of "Hello, world!".