diff --git a/pfSense-pkg-RESTAPI/files/usr/local/pkg/RESTAPI/Endpoints/SystemHASyncEndpoint.inc b/pfSense-pkg-RESTAPI/files/usr/local/pkg/RESTAPI/Endpoints/SystemHASyncEndpoint.inc
new file mode 100644
index 00000000..83f47bf8
--- /dev/null
+++ b/pfSense-pkg-RESTAPI/files/usr/local/pkg/RESTAPI/Endpoints/SystemHASyncEndpoint.inc
@@ -0,0 +1,25 @@
+<?php
+
+namespace RESTAPI\Endpoints;
+
+require_once 'RESTAPI/autoloader.inc';
+
+use RESTAPI\Core\Endpoint;
+
+/**
+ * Defines an Endpoint for interacting with pfSense High Availability synchronization settings.
+ */
+class SystemHASyncEndpoint extends Endpoint {
+    public function __construct() {
+        # Set Endpoint attributes
+        $this->url = '/api/v2/system/hasync';
+        $this->model_name = 'HASync';
+        $this->request_method_options = ['GET', 'PATCH'];
+        $this->tag = 'System';
+
+        $this->get_help_text = 'Reads pfSense High Availability synchronization settings.';
+        $this->patch_help_text = 'Updates pfSense High Availability synchronization settings and applies the configuration.';
+
+        parent::__construct();
+    }
+}
\ No newline at end of file
diff --git a/pfSense-pkg-RESTAPI/files/usr/local/pkg/RESTAPI/Models/HASync.inc b/pfSense-pkg-RESTAPI/files/usr/local/pkg/RESTAPI/Models/HASync.inc
new file mode 100644
index 00000000..9fe1345d
--- /dev/null
+++ b/pfSense-pkg-RESTAPI/files/usr/local/pkg/RESTAPI/Models/HASync.inc
@@ -0,0 +1,168 @@
+<?php
+
+namespace RESTAPI\Models;
+
+require_once 'RESTAPI/autoloader.inc';
+require_once 'filter.inc';
+
+use RESTAPI\Core\Model;
+use RESTAPI\Fields\BooleanField;
+use RESTAPI\Fields\InterfaceField;
+use RESTAPI\Fields\StringField;
+use RESTAPI\Validators\IPAddressValidator;
+
+/**
+ * Defines a Model for managing pfSense High Availability synchronization settings.
+ */
+class HASync extends Model {
+    public StringField $synchronizetoip;
+    public StringField $pfsyncpeerip;
+    public InterfaceField $pfsyncinterface;
+    public StringField $pfhostid;
+    public StringField $username;
+    public StringField $password;
+
+    public BooleanField $pfsyncenabled;
+    public BooleanField $adminsync;
+
+    public BooleanField $synchronizeusers;
+    public BooleanField $synchronizeauthservers;
+    public BooleanField $synchronizecerts;
+    public BooleanField $synchronizerules;
+    public BooleanField $synchronizeschedules;
+    public BooleanField $synchronizealiases;
+    public BooleanField $synchronizenat;
+    public BooleanField $synchronizeipsec;
+    public BooleanField $synchronizeopenvpn;
+    public BooleanField $synchronizedhcpd;
+    public BooleanField $synchronizedhcpdv6;
+    public BooleanField $synchronizekea6;
+    public BooleanField $synchronizewol;
+    public BooleanField $synchronizestaticroutes;
+    public BooleanField $synchronizevirtualip;
+    public BooleanField $synchronizetrafficshaper;
+    public BooleanField $synchronizetrafficshaperlimiter;
+    public BooleanField $synchronizednsforwarder;
+    public BooleanField $synchronizecaptiveportal;
+    public BooleanField $synchronizedhcrelay;
+    public BooleanField $synchronizedhcrelay6;
+
+    public function __construct(mixed $id = null, mixed $parent_id = null, mixed $data = [], mixed ...$options) {
+        # Set Model attributes
+        $this->config_path = 'hasync';
+        $this->many = false;
+        $this->always_apply = true;
+        $this->verbose_name = 'HA Sync Settings';
+        $this->verbose_name_plural = 'HA Sync Settings';
+
+        # State Synchronization Settings (pfsync)
+        $this->pfsyncenabled = $this->sync_flag('Enable pfsync state synchronization.');
+
+        $this->pfsyncinterface = new InterfaceField(
+            default: '',
+            allow_empty: true,
+            help_text: 'The interface used by pfsync state synchronization.',
+        );
+
+        $this->pfhostid = new StringField(
+            default: '',
+            allow_empty: true,
+            maximum_length: 8,
+            help_text: 'Custom pf host identifier carried in state data.',
+        );
+
+        $this->pfsyncpeerip = new StringField(
+            default: '',
+            allow_empty: true,
+            validators: [
+                new IPAddressValidator(
+                    allow_ipv4: true,
+                    allow_ipv6: false,
+                ),
+            ],
+            help_text: 'The peer IP address used by pfsync.',
+        );
+
+        # Configuration Synchronization Settings (XMLRPC Sync)
+        $this->synchronizetoip = new StringField(
+            default: '',
+            allow_empty: true,
+            validators: [
+                new IPAddressValidator(
+                    allow_ipv4: true,
+                    allow_ipv6: false,
+                ),
+            ],
+            help_text: 'The remote pfSense host IP address used for XMLRPC configuration synchronization.',
+        );
+
+        $this->username = new StringField(
+            default: '',
+            allow_empty: true,
+            help_text: 'The remote pfSense username used for XMLRPC synchronization.',
+        );
+
+        # pfSense stores the XMLRPC password in config.xml as <passwordfld>.
+        # The API exposes it as "password" but writes it internally as "passwordfld".
+        $this->password = new StringField(
+            default: '',
+            allow_empty: true,
+            write_only: true,
+            sensitive: true,
+            internal_name: 'passwordfld',
+            help_text: 'The remote pfSense password used for XMLRPC synchronization.',
+        );
+
+        $this->adminsync = $this->sync_flag(
+            'Synchronize admin accounts and automatically update the XMLRPC sync password.',
+        );
+
+        # Select options to sync
+        $this->synchronizeusers = $this->sync_flag('Synchronize users and groups.');
+        $this->synchronizeauthservers = $this->sync_flag('Synchronize authentication servers.');
+        $this->synchronizecerts = $this->sync_flag('Synchronize certificates.');
+        $this->synchronizerules = $this->sync_flag('Synchronize firewall rules.');
+        $this->synchronizeschedules = $this->sync_flag('Synchronize firewall schedules.');
+        $this->synchronizealiases = $this->sync_flag('Synchronize firewall aliases.');
+        $this->synchronizenat = $this->sync_flag('Synchronize NAT configuration.');
+        $this->synchronizeipsec = $this->sync_flag('Synchronize IPsec configuration.');
+        $this->synchronizeopenvpn = $this->sync_flag('Synchronize OpenVPN configuration.');
+        $this->synchronizedhcpd = $this->sync_flag('Synchronize DHCP server configuration.');
+        $this->synchronizedhcpdv6 = $this->sync_flag('Synchronize DHCPv6 server configuration.');
+        $this->synchronizekea6 = $this->sync_flag('Synchronize Kea DHCPv6 server configuration.');
+        $this->synchronizedhcrelay = $this->sync_flag('Synchronize DHCP relay configuration.');
+        $this->synchronizedhcrelay6 = $this->sync_flag('Synchronize DHCPv6 relay configuration.');
+        $this->synchronizewol = $this->sync_flag('Synchronize Wake-on-LAN configuration.');
+        $this->synchronizestaticroutes = $this->sync_flag('Synchronize static routes.');
+        $this->synchronizevirtualip = $this->sync_flag('Synchronize virtual IP addresses.');
+        $this->synchronizetrafficshaper = $this->sync_flag('Synchronize traffic shaper queues.');
+        $this->synchronizetrafficshaperlimiter = $this->sync_flag('Synchronize traffic shaper limiters.');
+        $this->synchronizednsforwarder = $this->sync_flag('Synchronize DNS Forwarder and DNS Resolver configuration.');
+        $this->synchronizecaptiveportal = $this->sync_flag('Synchronize captive portal configuration.');
+
+        parent::__construct($id, $parent_id, $data, ...$options);
+    }
+
+    /**
+     * pfSense HA Sync checkboxes are stored as the string "on" when enabled.
+     * When disabled, the XML key should be removed.
+     */
+    private function sync_flag(string $help_text): BooleanField {
+        return new BooleanField(
+            default: false,
+            indicates_true: 'on',
+            indicates_false: null,
+            help_text: $help_text,
+        );
+    }
+
+    /**
+     * Applies HA Sync configuration changes.
+     */
+    public function apply(): bool|null {
+        filter_configure_sync();
+        filter_configure();
+
+        return true;
+    }
+}
\ No newline at end of file