diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..485dee6
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+.idea
diff --git a/README.md b/README.md
index e69de29..b7b4319 100644
--- a/README.md
+++ b/README.md
@@ -0,0 +1,9 @@
+# pihole-opnsense-sync
+_Sync custom DNS entries in Pi-hole to OPNsense Unbound._
+
+## Install
+```shell
+pip install -r requirements.txt
+```
+
+Then get your API auth details.
diff --git a/pihole-opnsense-sync.service b/pihole-opnsense-sync.service
new file mode 100644
index 0000000..03bb6cc
--- /dev/null
+++ b/pihole-opnsense-sync.service
@@ -0,0 +1,12 @@
+[Unit]
+Description=Sync Pi-hole local DNS to OPNsense Unbound
+
+[Service]
+User=pihole
+Group=pihole
+ExecStart=/opt/icinga2-checks/Other/auto-acknowledge-apt.sh --api https://localhost:5665 --fail --user icingaweb2 --password XXXXX
+SyslogIdentifier=pihole-opnsense-sync
+Restart=always
+
+[Install]
+WantedBy=multi-user.target
\ No newline at end of file
diff --git a/requirements.txt b/requirements.txt
new file mode 100644
index 0000000..7a069ed
--- /dev/null
+++ b/requirements.txt
@@ -0,0 +1,2 @@
+requests==2.31.0
+watchdog==4.0.0
\ No newline at end of file
diff --git a/syncer.py b/syncer.py
new file mode 100755
index 0000000..00df610
--- /dev/null
+++ b/syncer.py
@@ -0,0 +1,91 @@
+#!/usr/bin/env python3
+import argparse
+import logging
+import time
+from datetime import datetime
+from pathlib import Path
+
+import requests
+import urllib3
+from watchdog.events import FileSystemEventHandler
+from watchdog.observers import Observer
+
+urllib3.disable_warnings()
+
+
+class WatchdogHandler(FileSystemEventHandler):
+    def __init__(self, args):
+        self.args = args
+
+    def on_modified(self, event):
+        if event.src_path == args.custom_path:
+            file_modified(args)
+
+
+def file_modified(args):
+    logger = logging.getLogger()
+    logger.setLevel(logging.INFO)
+    response = requests.get(args.opnsense + "/api/unbound/settings/searchHostOverride", auth=(args.api_key, args.api_secret), verify=args.insecure)
+
+    if response.status_code == 200:
+        data = response.json()
+        current_overrides = set([(x['server'], x['domain']) for x in data.get('rows', []) if x['description'] != 'SAVE'])
+        current_overrides_uuid = {x['domain']: x for x in data.get('rows', [])}
+        pihole_custom = set([(x[0], x[1]) for x in [y.split(' ') for y in Path(args.custom_path).read_text().split('\n')] if len(x) > 1])
+
+        to_remove = current_overrides - pihole_custom
+        to_add = pihole_custom - current_overrides
+
+        for item_ip, item_domain in to_remove:
+            item_data = current_overrides_uuid[item_domain]
+            p = requests.post(args.opnsense + f"/api/unbound/settings/delHostOverride/{item_data['uuid']}", auth=(args.api_key, args.api_secret), verify=args.insecure)
+            if p.status_code != 200:
+                raise Exception(f'Failed to delete item {item_domain}: {p.status_code} - {p.text}')
+            else:
+                logger.info(f'Deleted: {item_domain}')
+
+        now = datetime.now()
+        dt_string = now.strftime("%m/%d/%Y %H:%M:%S")
+
+        for item_ip, item_domain in to_add:
+            p_data = {
+                'host': {
+                    'enabled': '1',
+                    'hostname': '',
+                    'domain': item_domain,
+                    'rr': 'A',
+                    'mxprio': '',
+                    'mx': '',
+                    'server': item_ip,
+                    'description': f'Synced from Pi-hole {dt_string}'
+                }
+            }
+            p = requests.post(args.opnsense + "/api/unbound/settings/addHostOverride", json=p_data, auth=(args.api_key, args.api_secret), verify=args.insecure)
+            if p.status_code != 200:
+                raise Exception(f'Failed to add item {item_domain}: {p.status_code} - {p.text}')
+            else:
+                logger.info(f'Added: {item_domain}')
+    else:
+        raise Exception(f"Failed to fetch host overrides: {response.status_code} - {response.text}")
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(description='Sync custom DNS entries in Pi-hole to OPNsense Unbound.')
+    parser.add_argument('--opnsense', required=True, help='Address of your OPNsense server. Example: https://192.168.1.1')
+    parser.add_argument('--custom-path', default='/etc/pihole/custom.list', help="Path to Pi-hole's custom.list. Default: /etc/pihole/custom.list")
+    parser.add_argument('--api-key', required=True, help='OPNsense API key.')
+    parser.add_argument('--api-secret', required=True, help='OPNsense API secret.')
+    parser.add_argument('--insecure', action='store_true', help="Don't verify SSL.")
+    args = parser.parse_args()
+
+    event_handler = WatchdogHandler(args)
+    observer = Observer()
+    observer.schedule(event_handler, path='/etc/pihole/', recursive=False)
+    observer.start()
+
+    try:
+        while True:
+            time.sleep(1)
+    except KeyboardInterrupt:
+        observer.stop()
+    observer.join()