diff --git a/backend/app/models.py b/backend/app/models.py
new file mode 100644
index 0000000..ae92f99
--- /dev/null
+++ b/backend/app/models.py
@@ -0,0 +1,108 @@
+import json
+from datetime import datetime, timezone
+from sqlalchemy import Boolean, Column, DateTime, Float, Integer, String, Text
+from app.database import Base
+
+
+def _now():
+    return datetime.now(timezone.utc)
+
+
+class NetObjectModel(Base):
+    __tablename__ = "net_objects"
+
+    id = Column(String, primary_key=True, index=True)
+    name = Column(String, nullable=False)
+    slug = Column(String, nullable=True)
+    type = Column(String, nullable=False)
+    parent_id = Column(String, nullable=True, index=True)
+    status = Column(String, nullable=False, default="active")
+    vendor = Column(String, nullable=True)
+    model = Column(String, nullable=True)
+    serial = Column(String, nullable=True)
+    notes = Column(Text, nullable=True)
+    created_at = Column(DateTime(timezone=True), default=_now)
+    updated_at = Column(DateTime(timezone=True), default=_now, onupdate=_now)
+
+
+class RelationModel(Base):
+    __tablename__ = "relations"
+
+    id = Column(String, primary_key=True, index=True)
+    type = Column(String, nullable=False)
+    layer = Column(String, nullable=False)
+    source_id = Column(String, nullable=False, index=True)
+    target_id = Column(String, nullable=False, index=True)
+    direction = Column(String, nullable=False, default="forward")
+    source = Column(String, nullable=False)
+    confidence = Column(Float, nullable=False, default=1.0)
+    status = Column(String, nullable=False, default="active")
+    attributes_json = Column(Text, nullable=True, default="{}")
+    created_at = Column(DateTime(timezone=True), default=_now)
+    updated_at = Column(DateTime(timezone=True), default=_now, onupdate=_now)
+
+    @property
+    def attributes(self):
+        return json.loads(self.attributes_json or "{}")
+
+    @attributes.setter
+    def attributes(self, value):
+        self.attributes_json = json.dumps(value)
+
+
+class JobModel(Base):
+    __tablename__ = "jobs"
+
+    id = Column(String, primary_key=True, index=True)
+    type = Column(String, nullable=False)
+    status = Column(String, nullable=False, default="pending")
+    progress = Column(Integer, nullable=False, default=0)
+    message = Column(Text, nullable=True)
+    error = Column(Text, nullable=True)
+    payload_json = Column(Text, nullable=True)
+    result_json = Column(Text, nullable=True)
+    created_at = Column(DateTime(timezone=True), default=_now)
+    started_at = Column(DateTime(timezone=True), nullable=True)
+    finished_at = Column(DateTime(timezone=True), nullable=True)
+
+
+class DiscoveryProfileModel(Base):
+    __tablename__ = "discovery_profiles"
+
+    id = Column(String, primary_key=True, index=True)
+    name = Column(String, nullable=False)
+    strategy = Column(String, nullable=False, default="fast")
+    use_icmp = Column(Boolean, nullable=False, default=True)
+    use_arp = Column(Boolean, nullable=False, default=True)
+    use_snmp = Column(Boolean, nullable=False, default=False)
+    use_lldp = Column(Boolean, nullable=False, default=False)
+    use_portscan = Column(Boolean, nullable=False, default=False)
+    notes = Column(Text, nullable=True)
+
+
+class DiscoveryRunModel(Base):
+    __tablename__ = "discovery_runs"
+
+    id = Column(String, primary_key=True, index=True)
+    profile_id = Column(String, nullable=False, index=True)
+    subnet_ids_json = Column(Text, nullable=False, default="[]")
+    job_id = Column(String, nullable=True)
+    status = Column(String, nullable=False, default="pending")
+    summary_json = Column(Text, nullable=True)
+    created_at = Column(DateTime(timezone=True), default=_now)
+    started_at = Column(DateTime(timezone=True), nullable=True)
+    finished_at = Column(DateTime(timezone=True), nullable=True)
+
+
+class UserModel(Base):
+    __tablename__ = "users"
+
+    id = Column(Integer, primary_key=True, autoincrement=True)
+    username = Column(String, unique=True, nullable=False, index=True)
+    email = Column(String, unique=True, nullable=True)
+    hashed_password = Column(String, nullable=False)
+    role = Column(String, nullable=False, default="viewer")
+    disabled = Column(Boolean, nullable=False, default=False)
+    force_password_change = Column(Boolean, nullable=False, default=False)
+    created_at = Column(DateTime(timezone=True), default=_now)
+    updated_at = Column(DateTime(timezone=True), default=_now, onupdate=_now)