diff --git a/debug_toolbar/_stubs.py b/debug_toolbar/_stubs.py
index c536a0fe7..98d5dd33e 100644
--- a/debug_toolbar/_stubs.py
+++ b/debug_toolbar/_stubs.py
@@ -1,8 +1,7 @@
-from __future__ import annotations
-
-from typing import Any, NamedTuple, Optional
+from typing import Any, NamedTuple, Optional, Protocol
 
 from django import template as dj_template
+from django.http import HttpRequest, HttpResponse
 
 
 class InspectStack(NamedTuple):
@@ -24,3 +23,7 @@ class RenderContext(dj_template.context.RenderContext):
 class RequestContext(dj_template.RequestContext):
     template: dj_template.Template
     render_context: RenderContext
+
+
+class GetResponse(Protocol):
+    def __call__(self, request: HttpRequest) -> HttpResponse: ...
diff --git a/debug_toolbar/middleware.py b/debug_toolbar/middleware.py
index 2292bde8b..ffd688665 100644
--- a/debug_toolbar/middleware.py
+++ b/debug_toolbar/middleware.py
@@ -13,14 +13,19 @@
     sync_to_async,
 )
 from django.conf import settings
+from django.http import HttpRequest
 from django.utils.module_loading import import_string
 
 from debug_toolbar import settings as dt_settings
 from debug_toolbar.toolbar import DebugToolbar
 from debug_toolbar.utils import clear_stack_trace_caches, is_processable_html_response
 
+from ._stubs import GetResponse
 
-def show_toolbar(request):
+_HTML_TYPES = ("text/html", "application/xhtml+xml")
+
+
+def show_toolbar(request: HttpRequest):
     """
     Default function to determine whether to show the toolbar on a given page.
     """
@@ -108,7 +113,7 @@ class DebugToolbarMiddleware:
     sync_capable = True
     async_capable = True
 
-    def __init__(self, get_response):
+    def __init__(self, get_response: GetResponse):
         self.get_response = get_response
         # If get_response is a coroutine function, turns us into async mode so
         # a thread is not consumed during a whole request.
diff --git a/debug_toolbar/panels/__init__.py b/debug_toolbar/panels/__init__.py
index a53ba6652..65e82d073 100644
--- a/debug_toolbar/panels/__init__.py
+++ b/debug_toolbar/panels/__init__.py
@@ -3,6 +3,7 @@
 from django.utils.functional import classproperty
 
 from debug_toolbar import settings as dt_settings
+from debug_toolbar._stubs import GetResponse
 from debug_toolbar.utils import get_name_from_obj
 
 
@@ -13,7 +14,7 @@ class Panel:
 
     is_async = False
 
-    def __init__(self, toolbar, get_response):
+    def __init__(self, toolbar, get_response: GetResponse):
         self.toolbar = toolbar
         self.get_response = get_response
         self.from_store = False
diff --git a/debug_toolbar/toolbar.py b/debug_toolbar/toolbar.py
index 38f1a3803..af5529dbd 100644
--- a/debug_toolbar/toolbar.py
+++ b/debug_toolbar/toolbar.py
@@ -6,14 +6,16 @@
 import re
 import uuid
 from functools import cache
+from typing import TYPE_CHECKING, Any, Optional
 
 from django.apps import apps
 from django.conf import settings
 from django.core.exceptions import ImproperlyConfigured
 from django.dispatch import Signal
+from django.http import HttpRequest
 from django.template import TemplateSyntaxError
 from django.template.loader import render_to_string
-from django.urls import include, path, re_path, resolve
+from django.urls import URLPattern, include, path, re_path, resolve
 from django.urls.exceptions import Resolver404
 from django.utils.module_loading import import_string
 from django.utils.translation import get_language, override as lang_override
@@ -21,27 +23,35 @@
 from debug_toolbar import APP_NAME, settings as dt_settings
 from debug_toolbar.store import get_store
 
+from ._stubs import GetResponse
+
 logger = logging.getLogger(__name__)
 
 
+if TYPE_CHECKING:
+    from .panels import Panel
+
+
 class DebugToolbar:
     # for internal testing use only
     _created = Signal()
     store = None
 
-    def __init__(self, request, get_response, request_id=None):
+    def __init__(
+        self, request: HttpRequest, get_response: GetResponse, request_id=None
+    ):
         self.request = request
         self.config = dt_settings.get_config().copy()
         panels = []
-        for panel_class in reversed(self.get_panel_classes()):
+        for panel_class in reversed(list(self.get_panel_classes())):
             panel = panel_class(self, get_response)
             panels.append(panel)
             if panel.enabled:
                 get_response = panel.process_request
         self.process_request = get_response
-        self._panels = {panel.panel_id: panel for panel in reversed(panels)}
-        self.stats = {}
-        self.server_timing_stats = {}
+        self._panels = {panel.panel_id: panel for panel in panels}  # type: ignore[var-annotated]
+        self.stats: dict[str, Any] = {}
+        self.server_timing_stats: dict[str, Any] = {}
         self.request_id = request_id
         self.init_store()
         self._created.send(request, toolbar=self)
@@ -49,14 +59,14 @@ def __init__(self, request, get_response, request_id=None):
     # Manage panels
 
     @property
-    def panels(self):
+    def panels(self) -> list["Panel"]:
         """
         Get a list of all available panels.
         """
         return list(self._panels.values())
 
     @property
-    def enabled_panels(self):
+    def enabled_panels(self) -> list["Panel"]:
         """
         Get a list of panels enabled for the current request.
         """
@@ -72,7 +82,7 @@ def csp_nonce(self):
         """
         return getattr(self.request, "csp_nonce", None)
 
-    def get_panel_by_id(self, panel_id):
+    def get_panel_by_id(self, panel_id: str) -> "Panel":
         """
         Get the panel with the given id, which is the class name by default.
         """
@@ -80,7 +90,7 @@ def get_panel_by_id(self, panel_id):
 
     # Handle rendering the toolbar in HTML
 
-    def render_toolbar(self):
+    def render_toolbar(self) -> str:
         """
         Renders the overall Toolbar with panels inside.
         """
@@ -101,7 +111,7 @@ def render_toolbar(self):
             else:
                 raise
 
-    def should_render_panels(self):
+    def should_render_panels(self) -> bool:
         """Determine whether the panels should be rendered during the request
 
         If False, the panels will be loaded via Ajax.
@@ -128,7 +138,7 @@ def fetch(cls, request_id, panel_id=None):
     # Manually implement class-level caching of panel classes and url patterns
     # because it's more obvious than going through an abstraction.
 
-    _panel_classes = None
+    _panel_classes: Optional[list[type["Panel"]]] = None
 
     @classmethod
     def get_panel_classes(cls):
@@ -140,10 +150,10 @@ def get_panel_classes(cls):
             cls._panel_classes = panel_classes
         return cls._panel_classes
 
-    _urlpatterns = None
+    _urlpatterns: Optional[list[URLPattern]] = None
 
     @classmethod
-    def get_urls(cls):
+    def get_urls(cls) -> list[URLPattern]:
         if cls._urlpatterns is None:
             from . import views
 
@@ -153,13 +163,13 @@ def get_urls(cls):
                 path("render_panel/", views.render_panel, name="render_panel"),
             ]
             # Per-panel URLs
-            for panel_class in cls.get_panel_classes():
+            for panel_class in list(cls.get_panel_classes()):
                 urlpatterns += panel_class.get_urls()
             cls._urlpatterns = urlpatterns
         return cls._urlpatterns
 
     @classmethod
-    def is_toolbar_request(cls, request):
+    def is_toolbar_request(cls, request) -> bool:
         """
         Determine if the request is for a DebugToolbar view.
         """
@@ -171,7 +181,10 @@ def is_toolbar_request(cls, request):
             )
         except Resolver404:
             return False
-        return resolver_match.namespaces and resolver_match.namespaces[-1] == APP_NAME
+        return (
+            bool(resolver_match.namespaces)
+            and resolver_match.namespaces[-1] == APP_NAME
+        )
 
     @staticmethod
     @cache
@@ -185,7 +198,7 @@ def get_observe_request():
             return func_or_path
 
 
-def observe_request(request):
+def observe_request(request: HttpRequest):
     """
     Determine whether to update the toolbar from a client side request.
     """
@@ -216,7 +229,7 @@ def from_store(cls, request_id, panel_id=None):
         )
         toolbar._panels = {}
 
-        for panel_class in reversed(cls.get_panel_classes()):
+        for panel_class in reversed(list(cls.get_panel_classes())):
             panel = panel_class(toolbar, from_store_get_response)
             if panel_id and panel.panel_id != panel_id:
                 continue