Do I need to install anything on the webserver to handle json or is it handled by default?

What does that mean? Its all just bytes / http, so what further handling are you talking about?

Try 

#!/usr/bin/env perl --
use strict;
use warnings;

use JSON ();
use WWW::Mechanize 1.72;

Main( @ARGV );
exit( 0 );

sub Main {
    my $data = { a => 40, b => 2 };

    my $json = JSON->new->utf8;
    my $ua   = WWW::Mechanize->new;

    $ua->post(
        "http://myurl/public_html/cgi-bin/json-addition.cgi",
        Content_Type => 'application/json',
        Content      => $json->encode($data),
    );

    $ua->res->dump;
    if( $ua->is_json ){
        my $result = $json->decode( $ua->content );
        print $result->{c}, "\n";
    }

}

sub WWW::Mechanize::is_json { int( 'application/json' eq $_[0]->ct ) }

[download]

General notions you should be aware of as well as lists of things to check are found in Coping with Scoping , CGI to mod_perl Porting. mod_perl Coding guidelines , brian's Guide to Solving Any Perl Problem, CGI Help Guide , Troubleshooting Perl CGI scripts , On debugging, verify everything, talk to teddybear ...

Looks to me like /public_html/ is something extra you don't need

In reply to Re: json return value by Anonymous Monk
in thread json return value by stenasc

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