Actually Windows does have a utility that encodes and decodes base64 – CERTUTIL

I’m not sure what version of Windows introduced this command.

To encode a file:

certutil -encode inputFileName encodedOutputFileName

To decode a file:

certutil -decode encodedInputFileName decodedOutputFileName

There are a number of available verbs and options available to CERTUTIL.

To get a list of nearly all available verbs:

certutil -?

To get help on a particular verb (-encode for example):

certutil -encode -?

To get complete help for nearly all verbs:

certutil -v -?

Mysteriously, the -encodehex verb is not listed with certutil -? or certutil -v -?. But it is described using certutil -encodehex -?. It is another handy function 🙂

Update

Regarding David Morales’ comment, there is a poorly documented type option to the -encodehex verb that allows creation of base64 strings without header or footer lines.

certutil [Options] -encodehex inFile outFile [type]

A type of 1 will yield base64 without the header or footer lines.

See https://www.dostips.com/forum/viewtopic.php?f=3&t=8521#p56536 for a brief listing of the available type formats. And for a more in depth look at the available formats, see https://www.dostips.com/forum/viewtopic.php?f=3&t=8521#p57918.

Not investigated, but the -decodehex verb also has an optional trailing type argument.