diff --git a/tests/unit/test_sender.py b/tests/unit/test_sender.py
new file mode 100644
index 0000000..b2341b6
--- /dev/null
+++ b/tests/unit/test_sender.py
@@ -0,0 +1,38 @@
+"""Tests for notification content builder and Web Push sender."""
+
+from vigilar.alerts.sender import build_notification
+from vigilar.constants import EventType, Severity
+
+
+def test_build_notification_person_detected():
+    result = build_notification(EventType.PERSON_DETECTED, Severity.WARNING, "front_entrance", {})
+    assert result["title"] == "Person Detected"
+    assert "Front Entrance" in result["body"]
+
+
+def test_build_notification_pet_escape():
+    result = build_notification(EventType.PET_ESCAPE, Severity.ALERT, "back_deck", {"pet_name": "Angel"})
+    assert result["title"] == "Pet Alert"
+    assert "Angel" in result["body"]
+
+
+def test_build_notification_wildlife_predator():
+    result = build_notification(EventType.WILDLIFE_PREDATOR, Severity.CRITICAL, "front_entrance", {"species": "bear"})
+    assert result["title"] == "Wildlife Alert"
+    assert "bear" in result["body"].lower()
+
+
+def test_build_notification_power_loss():
+    result = build_notification(EventType.POWER_LOSS, Severity.CRITICAL, "ups", {})
+    assert result["title"] == "Power Alert"
+    assert "battery" in result["body"].lower()
+
+
+def test_build_notification_unknown_event_type():
+    result = build_notification(EventType.MOTION_START, Severity.WARNING, "cam1", {})
+    assert result["title"] == "Vigilar Alert"
+
+
+def test_build_notification_has_url():
+    result = build_notification(EventType.PERSON_DETECTED, Severity.WARNING, "front", {})
+    assert "url" in result
diff --git a/vigilar/alerts/sender.py b/vigilar/alerts/sender.py
new file mode 100644
index 0000000..9478680
--- /dev/null
+++ b/vigilar/alerts/sender.py
@@ -0,0 +1,97 @@
+"""Web Push notification sender with content mapping."""
+
+import json
+import logging
+import os
+import time
+
+from sqlalchemy.engine import Engine
+
+from vigilar.constants import AlertChannel, AlertStatus, EventType, Severity
+
+log = logging.getLogger("vigilar.alerts")
+
+_CONTENT_MAP: dict[str, tuple[str, str]] = {
+    EventType.PERSON_DETECTED: ("Person Detected", "Person on {source}"),
+    EventType.PET_ESCAPE: ("Pet Alert", "{pet_name} detected on {source} (exterior)"),
+    EventType.UNKNOWN_ANIMAL: ("Unknown Animal", "Unknown {species} on {source}"),
+    EventType.WILDLIFE_PREDATOR: ("Wildlife Alert", "{species} detected — {source}"),
+    EventType.WILDLIFE_NUISANCE: ("Wildlife", "{species} on {source}"),
+    EventType.UNKNOWN_VEHICLE_DETECTED: ("Unknown Vehicle", "Unknown vehicle on {source}"),
+    EventType.POWER_LOSS: ("Power Alert", "UPS on battery"),
+    EventType.LOW_BATTERY: ("Battery Critical", "UPS battery low"),
+}
+
+
+def _format_source(source_id: str) -> str:
+    return source_id.replace("_", " ").title() if source_id else "Unknown"
+
+
+def build_notification(event_type: str, severity: str, source_id: str, payload: dict) -> dict:
+    title, body_template = _CONTENT_MAP.get(event_type, ("Vigilar Alert", "{source}"))
+    source = _format_source(source_id)
+    body = body_template.format(
+        source=source,
+        pet_name=payload.get("pet_name", "Pet"),
+        species=payload.get("species", "animal").title(),
+    )
+    return {"title": title, "body": body, "url": f"/events?source={source_id}", "severity": severity}
+
+
+def _get_vapid_private_key(config) -> str | None:
+    key = os.environ.get("VIGILAR_VAPID_PRIVATE_KEY")
+    if key:
+        return key
+    key_file = config.alerts.web_push.vapid_private_key_file
+    if os.path.exists(key_file):
+        with open(key_file) as f:
+            return f.read().strip()
+    return None
+
+
+def send_alert(
+    engine: Engine,
+    event_type: str,
+    severity: str,
+    source_id: str,
+    payload: dict,
+    config=None,
+    event_id: int | None = None,
+) -> int:
+    from vigilar.storage.queries import delete_push_subscription, get_push_subscriptions, insert_alert_log
+
+    notification = build_notification(event_type, severity, source_id, payload)
+    subscriptions = get_push_subscriptions(engine)
+    if not subscriptions:
+        log.info("No push subscriptions — skipping notification for %s", event_type)
+        return 0
+
+    vapid_key = _get_vapid_private_key(config) if config else None
+    if not vapid_key:
+        log.warning("VAPID private key not available — cannot send push notifications")
+        return 0
+
+    claim_email = config.alerts.web_push.vapid_claim_email if config else "mailto:admin@vigilar.local"
+    sent_count = 0
+
+    for sub in subscriptions:
+        try:
+            from pywebpush import webpush
+            webpush(
+                subscription_info={
+                    "endpoint": sub["endpoint"],
+                    "keys": {"p256dh": sub["p256dh_key"], "auth": sub["auth_key"]},
+                },
+                data=json.dumps(notification),
+                vapid_private_key=vapid_key,
+                vapid_claims={"sub": claim_email},
+            )
+            insert_alert_log(engine, event_id, AlertChannel.WEB_PUSH, AlertStatus.SENT)
+            sent_count += 1
+        except Exception as e:
+            error_msg = str(e)
+            insert_alert_log(engine, event_id, AlertChannel.WEB_PUSH, AlertStatus.FAILED, error_msg)
+            if "410" in error_msg or "Gone" in error_msg:
+                delete_push_subscription(engine, sub["endpoint"])
+
+    return sent_count