decode base64 or hex data with sfk decode for Windows, Mac OS X and Linux.

sfk encode|decode [infile] format [options]

en- or decode text or data.

   -base64    encode all chars as a-z A-Z 0-9 +/
              with = used as padding character.
              add -nowrap to keep the output
              as one long line.
   -hex       encode all chars as hexadecimal
   -_hex      encode non-alphanumeric characters
              as prefix _ and hex value
   -\x25hex   encode non-alnum chars as % and hex
   -url       same as -\x25hex

   -linechars=n  with base64 format, number of chars
                 per output line. default is 40.
   -all       encode all chars, not just non-alnum
   -noeol     if text lines are received from a previous
              command then strip line end characters.
              default on encode with single input line
              and on hex decode without prefix.
              does nothing when loading from a file.
   -tofile x  write output to file x.
   -dump      show output data as hexdump.

see also
   sfk hexdump   produce hex data in many formats
   sfk hextobin  convert many hex formats to binary
   sfk uuencode  encode many files as plain text
   sfk md5       create checksum of file(s)

web reference

   sfk encode in.jpg -base64 -tofile out.txt
      encodes in.jpg as base64, writing to out.txt
   sfk decode in.txt -base64 -tofile out.dat
      decodes in.txt from base64, writing to out.dat
   sfk echo -spat "foo bar" +encode -url
      produces: foo%20bar
   sfk echo "foo_20bar" +decode -_hex
      produces: foo bar
   sfk fromclip +decode -url
      make an url copied from a web page readable
      by changing "foo%20bar" to "foo bar".