Base64 Decode

Decode Base64 string or use the Base64 to File tool for large files
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About

Our online Base64 decode tool helps you to convert encoded data that has been encoded using the Base64 encoding scheme into its original form. This tool is useful for debugging and testing the decoding process, as well as for gaining a better understanding of how Base64 decoding works.

How to use this Base64 Decode tool

  1. Input your Base64 encoded data into the input field.
  2. Click on DECODE button.
  3. The output will appear in a new field below the button.
  4. Example: Enter the following encoded string 'YmFzZTY0IGRlY29kZXI=', hit the decode button and you will get 'base64 decoder' as output
  5. Note: if you have large Base64 string (above 1mb) use the Base64 to file tool to upload the data as a file and decode it.

What is Base64?

The term Base64 is coming from a certain MIME content transfer encoding. Basically, Base64 is a collection of related encoding designs which represent the binary information in ASCII format by converting it into a base64 representation.

Types of URI characters

Base64 encoding schemes are generally used when there is a need to encode binary information that needs to be stored and transferred over media that are developed to deal with textual information. This guarantees that the data stays unchanged without modification during transfer. Base64 is generally used in a number of applications including electronic mail via MIME, and keeping complex information in XML.

The specific set of characters chosen for the 64 characters needed for the base can vary among implementations. The common concept is to select a set of 64 characters that is both part of a subset typical to most encodings. This mixture leaves the data impossible to be altered in transportation thru information systems, such as electronic mail, that were typically not 8-bit clean. The Base64 implementation in MIME uses a-z, A-Z and 0-9 for the first 62 values. Other Base64 variations share the same property but they use different symbols in the last two values.

Base64 table from RFC 4648
Index Binary Char Index Binary Char Index Binary Char Index Binary Char
0 000000 A 16 010000 Q 32 100000 g 48 110000 w
1 000001 B 17 010001 R 33 100001 h 49 110001 x
2 000010 C 18 010010 S 34 100010 i 50 110010 y
3 000011 D 19 010011 T 35 100011 j 51 110011 z
4 000100 E 20 010100 U 36 100100 k 52 110100 0
5 000101 F 21 010101 V 37 100101 l 53 110101 1
6 000110 G 22 010110 W 38 100110 m 54 110110 2
7 000111 H 23 010111 X 39 100111 n 55 110111 3
8 001000 I 24 011000 Y 40 101000 o 56 111000 4
9 001001 J 25 011001 Z 41 101001 p 57 111001 5
10 001010 K 26 011010 a 42 101010 q 58 111010 6
11 001011 L 27 011011 b 43 101011 r 59 111011 7
12 001100 M 28 011100 c 44 101100 s 60 111100 8
13 001101 N 29 011101 d 45 101101 t 61 111101 9
14 001110 O 30 011110 e 46 101110 u 62 111110 +
15 001111 P 31 011111 f 47 101111 v 63 111111 /
Padding =
Source: Base64 on Wikipedia
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