Perl

GET

use warnings;
use IO::Socket::SSL;
use HTTP::Request ();
use LWP::UserAgent ();
use JSON::MaybeXS qw(encode_json);

my $url = '<YOUR ENDPOINT URL>';
my $header = [
    'Content-Type' => 'application/json; charset=UTF-8',
    'Accept' => 'application/json',
    'apiKey'=>'<YOURTOKEN>'];
my $data = {
    options => {
        method => 'GET',
        headers => { 'Content-Type'=> 'application/json', Accept => 'application/json'}},
        url => '/rest/api/3/issue/DEV-16'
    };
my $encoded_data = encode_json($data);

my $request = HTTP::Request->new('POST', $url, $header, $encoded_data);
my $ua = LWP::UserAgent->new;
my $response = $ua->request($request);
my $res = $response->content;
print "r : ${res}";

POST

use warnings;
use IO::Socket::SSL;
use HTTP::Request ();
use LWP::UserAgent ();
use JSON::MaybeXS qw(encode_json);

my $url = '<YOUR ENDPOINT URL>';
my $header = [
  'Content-Type' => 'application/json; charset=UTF-8',
  'Accept' => 'application/json',
  'apiKey'=>'<YOURTOKEN>'];
my $data = {
  options=> {
    method=> "POST",
    headers=> {
      'Content-Type'=>"application/json",
      Accept=>"application/json"
    },
    body=> {
      fields=> {
        project=>{
          name=> "<your project name>"
        },
        summary=> "Create Issue via POST.",
        description=>"Creating of an issue via a POST request using the API Key Manager",
        issuetype=> {
        id=>"<your issue type id>"
        }
      }
    }
  },
  url=>"/rest/api/2/issue"
  };

my $encoded_data = encode_json($data);

my $request = HTTP::Request->new('POST', $url, $header, $encoded_data);
my $ua = LWP::UserAgent->new;
my $response = $ua->request($request);
my $res = $response->content;
print "r : ${res}";