diff --git a/backend/app/api/routes.py b/backend/app/api/routes.py
new file mode 100644
index 0000000..6996cee
--- /dev/null
+++ b/backend/app/api/routes.py
@@ -0,0 +1,259 @@
+"""FastAPI REST API routes for Deltacast SDI recorder control."""
+
+import logging
+from fastapi import APIRouter, HTTPException, Depends
+from typing import Any, Optional
+from pydantic import BaseModel, Field
+
+from ..models import RecorderConfig, PortStatus, SCTE35Marker
+from ..recorders.recorder import RecorderManager
+from ..recorders.scte35 import SCTE35Manager
+
+logger = logging.getLogger(__name__)
+
+# ============================================================================
+# Pydantic Models for Request Validation
+# ============================================================================
+
+
+class SCTE35InjectionRequest(BaseModel):
+    """Request model for SCTE35 marker injection endpoint."""
+    event_id: int = Field(..., description="Unique event identifier")
+    duration_seconds: float = Field(..., gt=0, description="Duration in seconds")
+    webhook_url: Optional[str] = Field(None, description="Optional webhook URL")
+    out_of_network: bool = Field(True, description="Out of network indicator")
+    splice_immediate: bool = Field(False, description="Splice immediate flag")
+
+
+router = APIRouter(prefix="/api")
+
+# These will be set by main.py during startup
+recorder_manager: RecorderManager | None = None
+scte35_manager: SCTE35Manager | None = None
+
+
+def get_recorder_manager() -> RecorderManager:
+    """Dependency to get the RecorderManager instance."""
+    if recorder_manager is None:
+        raise HTTPException(status_code=503, detail="Recorder not initialized")
+    return recorder_manager
+
+
+def get_scte35_manager() -> SCTE35Manager:
+    """Dependency to get the SCTE35Manager instance."""
+    if scte35_manager is None:
+        raise HTTPException(status_code=503, detail="SCTE35 manager not initialized")
+    return scte35_manager
+
+
+# ============================================================================
+# Health and Status Endpoints
+# ============================================================================
+
+
+@router.get("/health")
+async def health(manager: RecorderManager = Depends(get_recorder_manager)) -> dict[str, Any]:
+    """
+    Health check endpoint.
+    
+    Returns:
+        dict with status, port count, and recording count
+    """
+    try:
+        all_status = manager.get_all_status()
+        recording_count = sum(1 for status in all_status if status.is_recording)
+        
+        return {
+            "status": "ok",
+            "ports": len(all_status),
+            "recording_count": recording_count,
+        }
+    except Exception as e:
+        logger.error(f"Health check error: {e}")
+        raise HTTPException(status_code=500, detail="Internal server error")
+
+
+# ============================================================================
+# Port Status Endpoints
+# ============================================================================
+
+
+@router.get("/ports", response_model=list[PortStatus])
+async def list_ports(manager: RecorderManager = Depends(get_recorder_manager)) -> list[PortStatus]:
+    """
+    Get status of all recorder ports.
+    
+    Returns:
+        List of PortStatus objects for all ports
+    """
+    try:
+        return manager.get_all_status()
+    except Exception as e:
+        logger.error(f"Error listing ports: {e}")
+        raise HTTPException(status_code=500, detail="Internal server error")
+
+
+@router.get("/ports/{port_index}", response_model=PortStatus)
+async def get_port(
+    port_index: int,
+    manager: RecorderManager = Depends(get_recorder_manager),
+) -> PortStatus:
+    """
+    Get status of a specific recorder port.
+    
+    Args:
+        port_index: 0-based port index
+        
+    Returns:
+        PortStatus for the specified port
+        
+    Raises:
+        HTTPException(404): If port index is invalid
+    """
+    try:
+        return manager.get_status(port_index)
+    except ValueError as e:
+        logger.warning(f"Invalid port index {port_index}: {e}")
+        raise HTTPException(status_code=404, detail=f"Port {port_index} not found")
+    except Exception as e:
+        logger.error(f"Error getting port {port_index}: {e}")
+        raise HTTPException(status_code=500, detail="Internal server error")
+
+
+# ============================================================================
+# Recording Control Endpoints
+# ============================================================================
+
+
+@router.post("/ports/{port_index}/start")
+async def start_recording(
+    port_index: int,
+    config: RecorderConfig,
+    manager: RecorderManager = Depends(get_recorder_manager),
+) -> dict[str, Any]:
+    """
+    Start recording on a specific port.
+    
+    Args:
+        port_index: 0-based port index
+        config: RecorderConfig with codec and output settings
+        
+    Returns:
+        Message confirmation with port number
+        
+    Raises:
+        HTTPException(400): If port is already recording or config is invalid
+        HTTPException(404): If port index is invalid
+    """
+    try:
+        await manager.start_recording(port_index, config)
+        logger.info(f"Started recording on port {port_index}")
+        return {
+            "message": "Recording started",
+            "port": port_index,
+        }
+    except ValueError as e:
+        logger.warning(f"Invalid port {port_index}: {e}")
+        raise HTTPException(status_code=404, detail=f"Port {port_index} not found")
+    except RuntimeError as e:
+        logger.warning(f"Cannot start recording on port {port_index}: {e}")
+        raise HTTPException(status_code=400, detail=str(e))
+    except Exception as e:
+        logger.error(f"Error starting recording on port {port_index}: {e}")
+        raise HTTPException(status_code=500, detail="Internal server error")
+
+
+@router.post("/ports/{port_index}/stop")
+async def stop_recording(
+    port_index: int,
+    manager: RecorderManager = Depends(get_recorder_manager),
+) -> dict[str, Any]:
+    """
+    Stop recording on a specific port.
+    
+    Args:
+        port_index: 0-based port index
+        
+    Returns:
+        Message confirmation with port number
+        
+    Raises:
+        HTTPException(404): If port index is invalid
+    """
+    try:
+        await manager.stop_recording(port_index)
+        logger.info(f"Stopped recording on port {port_index}")
+        return {
+            "message": "Recording stopped",
+            "port": port_index,
+        }
+    except ValueError as e:
+        logger.warning(f"Invalid port {port_index}: {e}")
+        raise HTTPException(status_code=404, detail=f"Port {port_index} not found")
+    except Exception as e:
+        logger.error(f"Error stopping recording on port {port_index}: {e}")
+        raise HTTPException(status_code=500, detail="Internal server error")
+
+
+# ============================================================================
+# SCTE35 Ad Break Endpoints
+# ============================================================================
+
+
+@router.post("/scte35/inject", response_model=SCTE35Marker)
+async def inject_scte35_marker(
+    request: SCTE35InjectionRequest,
+    manager: SCTE35Manager = Depends(get_scte35_manager),
+) -> SCTE35Marker:
+    """
+    Inject a SCTE35 ad break marker.
+
+    Args:
+        request: SCTE35InjectionRequest with:
+            - event_id: int (unique event identifier)
+            - duration_seconds: float (duration in seconds)
+            - webhook_url: str | None (optional callback URL)
+            - out_of_network: bool (whether out-of-network ad)
+            - splice_immediate: bool (whether splice immediately)
+
+    Returns:
+        SCTE35Marker with timestamp and metadata
+
+    Raises:
+        HTTPException(400): If parameters are invalid
+    """
+    try:
+        marker = await manager.inject_marker(
+            event_id=request.event_id,
+            duration_seconds=request.duration_seconds,
+            webhook_url=request.webhook_url,
+            out_of_network=request.out_of_network,
+            splice_immediate=request.splice_immediate,
+        )
+
+        logger.info(f"Injected SCTE35 marker with event_id {request.event_id}")
+        return marker
+
+    except ValueError as e:
+        logger.warning(f"Invalid SCTE35 parameters: {e}")
+        raise HTTPException(status_code=400, detail=str(e))
+    except Exception as e:
+        logger.error(f"Error injecting SCTE35 marker: {e}")
+        raise HTTPException(status_code=500, detail="Internal server error")
+
+
+@router.get("/scte35/history", response_model=list[SCTE35Marker])
+async def get_scte35_history(
+    manager: SCTE35Manager = Depends(get_scte35_manager),
+) -> list[SCTE35Marker]:
+    """
+    Get history of injected SCTE35 markers.
+    
+    Returns:
+        List of SCTE35Marker objects in chronological order
+    """
+    try:
+        return manager.get_marker_history()
+    except Exception as e:
+        logger.error(f"Error retrieving SCTE35 history: {e}")
+        raise HTTPException(status_code=500, detail="Internal server error")