diff --git a/ChangeLog.md b/ChangeLog.md
index efb6a14..cc5b656 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -4,7 +4,10 @@ This document describes notable changes. For details, see the [source code
 repository history](https://github.com/ddclient/ddclient/commits/master).
 
 ## Not yet released
+### New features
 
+  * Added support for domaindiscount24.com
+ 
 ## 2022-05-15 v3.10.0_2
 
 ### Bug fixes
diff --git a/ddclient.in b/ddclient.in
index 76d97d5..276186c 100755
--- a/ddclient.in
+++ b/ddclient.in
@@ -523,6 +523,10 @@ my %variables = (
         'static'              => setv(T_BOOL,  0, 1, 0,                    undef),
         'wildcard'            => setv(T_BOOL,  0, 1, 0,                    undef),
     },
+    'keysystems-common-defaults' => {
+        'server'              => setv(T_FQDNP, 1, 0, 1, 'dynamicdns.key-systems.net', undef),
+        'login'               => setv(T_LOGIN, 0, 0, 0, 'unused',      undef),
+    },
     'dnsexit-common-defaults'       => {
         'ssl'         => setv(T_BOOL,   0, 0, 1, undef),
         'server'      => setv(T_FQDNP,  1, 0, 'update.dnsexit.com', undef),
@@ -862,6 +866,15 @@ my %services = (
             'zone'         => setv(T_OFQDN, 0, 0, undef,                  undef),
         },
     },
+    'keysystems' => {
+    'updateable' => undef,
+    'update' => \&nic_keysystems_update,
+    'examples'  => \&nic_keysystems_examples,
+    'variables' => merge(
+            $variables{'keysystems-common-defaults'},
+            $variables{'service-common-defaults'},
+            ),
+    },
     'dnsexit' => {
         'updateable' => undef,
         'update'     => \&nic_dnsexit_update,
@@ -6976,6 +6989,72 @@ sub nic_gandi_update {
         }
     }
 }
+######################################################################
+## nic_keysystems_examples
+######################################################################
+sub nic_keysystems_examples {
+    return <<EoEXAMPLE;
+o 'keysystems'
+
+The 'keysystems' protocol is used by the non-free
+dynamic DNS service offered by www.domaindiscount24.com and www.rrpproxy.net.
+Check https://www.domaindiscount24.com/faq/en/dynamic-dns for API
+
+Configuration variables applicable to the 'keysystems' protocol are:
+protocol=keysystems
+server=dynamicdns.key-systems.net
+password=service-password          ## password (token) registered with the service
+subdomain.example.com              ## the host registered with the service.
+
+Example ${program}.conf file entries:
+## single host update
+protocol=keysystems,             \\\\
+password=service-password        \\\\
+example.com
+
+EoEXAMPLE
+}
+
+######################################################################
+## nic_keysystems_update
+## response contains "code 200" on succesfull completion
+######################################################################
+sub nic_keysystems_update {
+ debug("\nnic_keysystems_update -------------------");
+
+ ## update each configured host
+ ## should improve to update in one pass
+ foreach my $h (@_) {
+   my $ip = delete $config{$h}{'wantip'};
+   info("KEYSYSTEMS setting IP address to %s for %s", $ip, $h);
+
+   my $url = "http://$config{$h}{'server'}/update.php?hostname=$h&password=$config{$h}{'password'}&ip=$ip";
+
+   # Try to get URL
+   my $reply = geturl(opt('proxy'), $url);
+
+   # No response, declare as failed
+   if (!defined($reply) || !$reply) {
+     failed("KEYSYSTEMS updating %s: Could not connect to %s.", $h, $config{$h}{'server'});
+     last;
+   }
+   last if !header_ok($h, $reply);
+
+   if ($reply =~ /code = 200/)
+   {
+       $config{$h}{'ip'}   = $ip;
+       $config{$h}{'mtime'} = $now;
+       $config{$h}{'status'} = 'good';
+       success("updating %s: good: IP address set to %s", $h, $ip);
+    }
+    else
+    {
+       $config{$h}{'status'} = 'failed';
+       failed("updating %s: Server said: '$reply'", $h);
+    }
+  }
+}
+
 
 # Execute main() if this file is run as a script or run via PAR (https://metacpan.org/pod/PAR),
 # otherwise do nothing. This "modulino" pattern makes it possible to import this file as a module