Special chars in base64 decoded string

Question

When I decode (using one of the online decoders) a base64 string, the decoded data returns several special chars like sqaure blocks and `"

Answer 1

base64 encodes binary data to visible characters. If you decode it, the string will be turned back into the binary data, where some of the bytes won't have an ascii/unicode representation and will show as squares. This is normal behaviour. You should decode the data in the program you want to use the data in.