Regex to validate JSON

Question

I am looking for a Regex that allows me to validate json.

I am very new to Regex\'s and i know enough that parsing with Regex is bad but can it be used to validate?

Answer 1

I tried @mario's answer, but it didn't work for me, because I've downloaded test suite from JSON.org (archive) and there were 4 failed tests (fail1.json, fail18.json, fail25.json, fail27.json).

I've investigated the errors and found out, that fail1.json is actually correct (according to manual's note and RFC-7159 valid string is also a valid JSON). File fail18.json was not the case either, cause it contains actually correct deeply-nested JSON:

[[[[[[[[[[[[[[[[[[[["Too deep"]]]]]]]]]]]]]]]]]]]]

So two files left: fail25.json and fail27.json:

["  tab character   in  string  "]

and

["line
break"]

Both contains invalid characters. So I've updated the pattern like this (string subpattern updated):

$pcreRegex = '/
          (?(DEFINE)
             (?   -? (?= [1-9]|0(?!\d) ) \d+ (\.\d+)? ([eE] [+-]? \d+)? )
             (?   true | false | null )
             (?    " ([^"\n\r\t\\\\]* | \\\\ ["\\\\bfnrt\/] | \\\\ u [0-9a-f]{4} )* " )
             (?     \[  (?:  (?&json)  (?: , (?&json)  )*  )?  \s* \] )
             (?      \s* (?&string) \s* : (?&json)  )
             (?