Some remarks:

my $ok = utf8::decode($json); is not the best way to validate utf8. Because:
  1. It only validates Perl's notion of utf-8. Which is not exactly what the Unicode Consortium says. 
    use feature 'say';
binmode STDOUT, 'encoding(utf-8)';

my $str = "\xFC\x90\x80\x80\x80\x80";
my $ok = utf8::decode( $str );

say $ok ? 'ok' : 'not ok';
say $str;

    [download]
    output: 
    ok
Code point 0x10000000 is not Unicode, may not be portable at demo.pl l
+ine 8.
"\x{10000000}" does not map to utf8 at demo.pl line 8.
\x{10000000}

    [download]
  2. It always decodes a string in place. So doing 
    my $ok = utf8::decode($json);
Dump( $json );

    [download]
    is not super useful
Second, according to JSON's docs, encode_json is equivalent to JSON->new->utf8->encode($perl_scalar), while to_json is JSON->new->encode($perl_scalar). I don't know how these modules work, but the presence/absence of ->utf8 probably makes some difference?

In reply to Re: JSON::XS produces valid utf-8, and JSON doesn't - why? by Anonymous Monk
in thread JSON::XS produces valid utf-8, and JSON doesn't - why? by isync

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