Online Base64 Encoder / Decoder Tool
If you encounter any errors with this tool attaching the file that causes problems.
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Base64 is a method of encoding binary data sent as an attachment through email. Base64 encoding divides three bytes of data into four bytes of ASCII text, making the resulting file size approximately 33% larger.
The particular choice of base is due to the history of character set encoding: one can choose 64 characters that are both part of the subset common to most encodings, and also printable. This combination leaves the data unlikely to be modified in transit through systems, such as email, which were traditionally not 8-bit clean.
Characters used by Base64: ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/
The precise choice of characters was difficult. The earliest instances of this type of encoding were created for dialup communication between systems running the same OS - e.g. Uuencode for UNIX, BinHex for the TRS-80 (later adapted for the Macintosh) - and could therefore make more assumptions about what characters were safe to use. For instance, Uuencode uses uppercase letters, digits, and many punctuation characters, but no lowercase, since UNIX was sometimes used with terminals that did not support distinct letter case. Unfortunately for interoperability with non-UNIX systems, some of the punctuation characters do not exist in other traditional character sets. The MIME Base64 encoding replaces most of the punctuation characters with the lowercase letters, a reasonable requirement by the time it was designed.