I'm not sure if I'm the only one to notice this, but there appears to be no way to represent an arbitrary string of bytes in JSON.
JSON is a serialization format that (for some reason) encodes Unicode strings, numbers, lists and records as a Unicode string. Which is good, as long as the only data types your application deals with are one of those above.
What about:
char* (c) ByteString or (Haskell)
Which doesn't have a mapping to JSON. Strangely, many of the programs written over the last—oh—20 years deal in 'lists of bytes'. Consider JPEG image data or a million other examples.
There are workarounds: you could convert a list of bytes to a list of integers and encode that, or use base64 or use uuencode. You could even pick 256 Unicode code points and map the bytes to those. U+0000 to U+00FF would seem to be one option, equally U+0001 to U+0100.
I'm not saying that it isn't possible, just that a 'standard' that doesn't define how to encode the most common, universal data type ever is a wee bit broken.
In general, any standard that includes pseudo-formalisms on its homepage is broken.