diff --git a/backend/apps/library/serializers.py b/backend/apps/library/serializers.py
index c8f2e75..e966e91 100644
--- a/backend/apps/library/serializers.py
+++ b/backend/apps/library/serializers.py
@@ -1,9 +1,10 @@
 import os
 
+from django.core import signing
 from rest_framework import serializers
 
 from .models import MediaItem, MediaLocation, TempUpload
-from .services import VIDEO_EXTENSIONS
+from .services import UPLOAD_FILE_SALT, VIDEO_EXTENSIONS
 
 
 class MediaLocationSerializer(serializers.ModelSerializer):
@@ -125,4 +126,15 @@ class TempUploadSerializer(serializers.ModelSerializer):
         return f"J-{obj.library_item_id}" if obj.library_item_id else None
 
     def get_file_url(self, obj):
-        return f"/api/uploads/{obj.id}/file/" if obj.file else None
+        """Signed URL so <img>/<video> tags can fetch the staged file."""
+        if not obj.file:
+            return None
+        request = self.context.get("request")
+        user = getattr(request, "user", None)
+        if user is None or not getattr(user, "is_authenticated", False):
+            return None
+        signature = signing.dumps(
+            {"temp": str(obj.id), "user": user.id},
+            salt=UPLOAD_FILE_SALT,
+        )
+        return f"/api/uploads/{obj.id}/file/?sig={signature}"
diff --git a/backend/apps/library/services.py b/backend/apps/library/services.py
index 5785b9c..635ff37 100644
--- a/backend/apps/library/services.py
+++ b/backend/apps/library/services.py
@@ -13,8 +13,18 @@ from django.utils.text import get_valid_filename
 
 from .models import MediaItem, MediaLocation
 
-ALLOWED_EXTENSIONS = {".jpg", ".jpeg", ".png", ".gif", ".apng", ".mp4", ".webm"}
+ALLOWED_EXTENSIONS = {
+    ".jpg",
+    ".jpeg",
+    ".png",
+    ".gif",
+    ".apng",
+    ".webp",
+    ".mp4",
+    ".webm",
+}
 VIDEO_EXTENSIONS = {".mp4", ".webm"}
+UPLOAD_FILE_SALT = "j621.upload-file"
 CHUNK_SIZE = 1024 * 1024
 RANGE_RE = re.compile(r"bytes=(\d*)-(\d*)$")
 
diff --git a/backend/apps/library/uploads.py b/backend/apps/library/uploads.py
index 38a54cf..cd53eef 100644
--- a/backend/apps/library/uploads.py
+++ b/backend/apps/library/uploads.py
@@ -14,10 +14,13 @@ import shutil
 from pathlib import Path
 
 from django.conf import settings
+from django.contrib.auth import get_user_model
+from django.core import signing
 from django.http import Http404
 from rest_framework import mixins, status, viewsets
 from rest_framework.decorators import action
 from rest_framework.parsers import FormParser, JSONParser, MultiPartParser
+from rest_framework.permissions import AllowAny
 from rest_framework.response import Response
 
 from . import services
@@ -116,12 +119,42 @@ class TempUploadViewSet(
             temp.file.delete(save=False)
         temp.save()
         return Response(
-            TempUploadSerializer(temp).data, status=status.HTTP_201_CREATED
+            self.get_serializer(temp).data, status=status.HTTP_201_CREATED
         )
 
-    @action(detail=True, methods=["get"])
+    @action(detail=True, methods=["get", "head"], permission_classes=[AllowAny])
     def file(self, request, pk=None):
-        temp = self.get_object()
+        """Serve the staged file; accepts a signed URL for media tags."""
+        user = request.user if request.user.is_authenticated else None
+        if user is None:
+            signature = request.query_params.get("sig")
+            if signature:
+                try:
+                    payload = signing.loads(
+                        signature,
+                        salt=services.UPLOAD_FILE_SALT,
+                        max_age=86400,
+                    )
+                except signing.BadSignature:
+                    payload = None
+                if payload and str(payload.get("temp")) == str(pk):
+                    user = (
+                        get_user_model()
+                        .objects.filter(pk=payload.get("user"))
+                        .first()
+                    )
+        if user is None or not user.can_upload:
+            return Response(
+                {"detail": "Authentication required."},
+                status=status.HTTP_401_UNAUTHORIZED,
+            )
+
+        temp = TempUpload.objects.filter(pk=pk).first()
+        is_owner = temp is not None and temp.user_id == user.id
+        if temp is None or not (
+            is_owner or user.is_staff or user.is_superuser
+        ):
+            raise Http404
         if not temp.file:
             raise Http404
         return services.serve_file(request, temp.file.path)
@@ -139,7 +172,7 @@ class TempUploadViewSet(
         if temp.status == TempUpload.STATUS_PENDING and temp.iqdb_data:
             temp.status = TempUpload.STATUS_VISUAL_MATCH
         temp.save(update_fields=["iqdb_data", "status", "updated_at"])
-        return Response(TempUploadSerializer(temp).data)
+        return Response(self.get_serializer(temp).data)
 
     @action(detail=True, methods=["post"])
     def resolve(self, request, pk=None):
@@ -204,7 +237,7 @@ class TempUploadViewSet(
                 status=status.HTTP_400_BAD_REQUEST,
             )
         temp.refresh_from_db()
-        return Response(TempUploadSerializer(temp).data)
+        return Response(self.get_serializer(temp).data)
 
     def perform_destroy(self, instance):
         if instance.file:
diff --git a/frontend/src/features/upload/UploadPage.tsx b/frontend/src/features/upload/UploadPage.tsx
index 26a8f2e..d483ea8 100644
--- a/frontend/src/features/upload/UploadPage.tsx
+++ b/frontend/src/features/upload/UploadPage.tsx
@@ -724,7 +724,7 @@ export default function UploadPage() {
           Drag &amp; drop files here
         </p>
         <p className="text-xs text-ctp-overlay0">
-          or click to select — PNG, JPG, GIF, APNG, MP4, WEBM
+          or click to select — PNG, JPG, GIF, APNG, WEBP, MP4, WEBM
         </p>
         <input
           ref={inputRef}