[maskros]

"\0" is not a valid JSON string escape sequence.

However, "\u0000" is.

[peoplefromibiza]

not according to jq or firefox

   >> JSON.parse("\u0000")
   Uncaught SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data
       <anonymous> debugger eval code:1

at that point "null" looks like a better more compatible option.

[unilynx]

they're not comparable at all. you can't embed a null into a string

\u0000 works fine with firefox with the proper syntax

  JSON.parse(`"\\u0000"`)
  "\u0000"

and jq supports it too

  printf '{"null":"\u0000"}' | jq
  {
    "null": "\u0000"
  }