diff --git a/frontend/src/components/AccessListForm.tsx b/frontend/src/components/AccessListForm.tsx
index cd55f25c..cbb0e293 100644
--- a/frontend/src/components/AccessListForm.tsx
+++ b/frontend/src/components/AccessListForm.tsx
@@ -162,7 +162,7 @@ export function AccessListForm({ initialData, onSubmit, onCancel, onDelete, isLo
       const result = await getMyIP();
       setNewIP(result.ip);
       toast.success(`Your IP: ${result.ip} (from ${result.source})`);
-    } catch (error) {
+    } catch {
       toast.error('Failed to fetch your IP address');
     } finally {
       setLoadingMyIP(false);
diff --git a/frontend/src/components/CertificateList.tsx b/frontend/src/components/CertificateList.tsx
index d97fb743..4568f534 100644
--- a/frontend/src/components/CertificateList.tsx
+++ b/frontend/src/components/CertificateList.tsx
@@ -21,7 +21,7 @@ export default function CertificateList() {
       queryClient.invalidateQueries({ queryKey: ['certificates'] })
       toast.success('Certificate deleted')
     },
-    onError: (error: any) => {
+    onError: (error: Error) => {
       toast.error(`Failed to delete certificate: ${error.message}`)
     },
   })
diff --git a/frontend/src/components/__tests__/ProxyHostForm.test.tsx b/frontend/src/components/__tests__/ProxyHostForm.test.tsx
index b1b418f1..0d29ddf3 100644
--- a/frontend/src/components/__tests__/ProxyHostForm.test.tsx
+++ b/frontend/src/components/__tests__/ProxyHostForm.test.tsx
@@ -94,7 +94,7 @@ const renderWithClient = (ui: React.ReactElement) => {
 import { testProxyHostConnection } from '../../api/proxyHosts'
 
 describe('ProxyHostForm', () => {
-  const mockOnSubmit = vi.fn((_data: any) => Promise.resolve())
+  const mockOnSubmit = vi.fn(() => Promise.resolve())
   const mockOnCancel = vi.fn()
 
   beforeEach(() => {
@@ -183,7 +183,7 @@ describe('ProxyHostForm', () => {
   })
 
   it('tests connection successfully', async () => {
-    (testProxyHostConnection as any).mockResolvedValue({})
+    vi.mocked(testProxyHostConnection).mockResolvedValue(undefined)
 
     renderWithClient(
       <ProxyHostForm onSubmit={mockOnSubmit} onCancel={mockOnCancel} />
@@ -202,7 +202,7 @@ describe('ProxyHostForm', () => {
   })
 
   it('handles connection test failure', async () => {
-    (testProxyHostConnection as any).mockRejectedValue(new Error('Connection failed'))
+    vi.mocked(testProxyHostConnection).mockRejectedValue(new Error('Connection failed'))
 
     renderWithClient(
       <ProxyHostForm onSubmit={mockOnSubmit} onCancel={mockOnCancel} />
diff --git a/frontend/src/pages/Account.tsx b/frontend/src/pages/Account.tsx
index 6a34b521..d7a107b7 100644
--- a/frontend/src/pages/Account.tsx
+++ b/frontend/src/pages/Account.tsx
@@ -91,7 +91,7 @@ export default function Account() {
       queryClient.invalidateQueries({ queryKey: ['profile'] })
       toast.success('Profile updated successfully')
     },
-    onError: (error: any) => {
+    onError: (error: Error) => {
       toast.error(`Failed to update profile: ${error.message}`)
     },
   })
@@ -103,7 +103,7 @@ export default function Account() {
       queryClient.invalidateQueries({ queryKey: ['settings'] })
       toast.success('Certificate email updated')
     },
-    onError: (error: any) => {
+    onError: (error: Error) => {
       toast.error(`Failed to update certificate email: ${error.message}`)
     },
   })
@@ -114,7 +114,7 @@ export default function Account() {
       queryClient.invalidateQueries({ queryKey: ['profile'] })
       toast.success('API Key regenerated successfully')
     },
-    onError: (error: any) => {
+    onError: (error: Error) => {
       toast.error(`Failed to regenerate API key: ${error.message}`)
     },
   })
@@ -223,7 +223,8 @@ export default function Account() {
       setOldPassword('')
       setNewPassword('')
       setConfirmPassword('')
-    } catch (error: any) {
+    } catch (err) {
+      const error = err as Error
       toast.error(error.message || 'Failed to update password')
     } finally {
       setLoading(false)
diff --git a/frontend/src/pages/Certificates.tsx b/frontend/src/pages/Certificates.tsx
index c6f01e17..b2dffce0 100644
--- a/frontend/src/pages/Certificates.tsx
+++ b/frontend/src/pages/Certificates.tsx
@@ -27,7 +27,7 @@ export default function Certificates() {
       setKeyFile(null)
       toast.success('Certificate uploaded successfully')
     },
-    onError: (error: any) => {
+    onError: (error: Error) => {
       toast.error(`Failed to upload certificate: ${error.message}`)
     },
   })
diff --git a/frontend/src/pages/Domains.tsx b/frontend/src/pages/Domains.tsx
index e6c5bec2..155f5ffb 100644
--- a/frontend/src/pages/Domains.tsx
+++ b/frontend/src/pages/Domains.tsx
@@ -15,7 +15,7 @@ export default function Domains() {
     try {
       await createDomain(newDomain)
       setNewDomain('')
-    } catch (err) {
+    } catch {
       alert('Failed to create domain')
     } finally {
       setIsSubmitting(false)
@@ -26,7 +26,7 @@ export default function Domains() {
     if (confirm('Are you sure you want to delete this domain?')) {
       try {
         await deleteDomain(uuid)
-      } catch (err) {
+      } catch {
         alert('Failed to delete domain')
       }
     }
diff --git a/frontend/src/pages/Login.tsx b/frontend/src/pages/Login.tsx
index 3e82e72a..a3d806d6 100644
--- a/frontend/src/pages/Login.tsx
+++ b/frontend/src/pages/Login.tsx
@@ -40,8 +40,9 @@ export default function Login() {
       await queryClient.invalidateQueries({ queryKey: ['setupStatus'] })
       toast.success('Logged in successfully')
       navigate('/')
-    } catch (err: any) {
-      toast.error(err.response?.data?.error || 'Login failed')
+    } catch (err) {
+      const error = err as { response?: { data?: { error?: string } } }
+      toast.error(error.response?.data?.error || 'Login failed')
     } finally {
       setLoading(false)
     }
diff --git a/frontend/src/pages/Notifications.tsx b/frontend/src/pages/Notifications.tsx
index fdccb419..770deef9 100644
--- a/frontend/src/pages/Notifications.tsx
+++ b/frontend/src/pages/Notifications.tsx
@@ -9,7 +9,7 @@ import { useForm } from 'react-hook-form';
 const ProviderForm: React.FC<{
   initialData?: Partial<NotificationProvider>;
   onClose: () => void;
-  onSubmit: (data: any) => void;
+  onSubmit: (data: Partial<NotificationProvider>) => void;
 }> = ({ initialData, onClose, onSubmit }) => {
   const { register, handleSubmit, watch, setValue, formState: { errors } } = useForm({
     defaultValues: initialData || {
@@ -40,7 +40,7 @@ const ProviderForm: React.FC<{
 
   const handleTest = () => {
     const formData = watch();
-    testMutation.mutate(formData as any);
+    testMutation.mutate(formData as Partial<NotificationProvider>);
   };
 
   const type = watch('type');
@@ -197,7 +197,7 @@ const Notifications: React.FC = () => {
   });
 
   const updateMutation = useMutation({
-    mutationFn: ({ id, data }: { id: string; data: any }) => updateProvider(id, data),
+    mutationFn: ({ id, data }: { id: string; data: Partial<NotificationProvider> }) => updateProvider(id, data),
     onSuccess: () => {
       queryClient.invalidateQueries({ queryKey: ['notificationProviders'] });
       setEditingId(null);
@@ -214,7 +214,7 @@ const Notifications: React.FC = () => {
   const testMutation = useMutation({
     mutationFn: testProvider,
     onSuccess: () => alert('Test notification sent!'),
-    onError: (err: any) => alert(`Failed to send test: ${err.response?.data?.error || err.message}`),
+    onError: (err: Error) => alert(`Failed to send test: ${err.message}`),
   });
 
   if (isLoading) return <div>Loading...</div>;
diff --git a/frontend/src/pages/ProxyHosts.tsx b/frontend/src/pages/ProxyHosts.tsx
index 6ac38673..35e89e1c 100644
--- a/frontend/src/pages/ProxyHosts.tsx
+++ b/frontend/src/pages/ProxyHosts.tsx
@@ -190,7 +190,7 @@ export default function ProxyHosts() {
         try {
           await deleteHost(uuid)
           deleted++
-        } catch (err) {
+        } catch {
           failed++
         }
       }
diff --git a/frontend/src/pages/Setup.tsx b/frontend/src/pages/Setup.tsx
index b7d7dcb4..53b138a9 100644
--- a/frontend/src/pages/Setup.tsx
+++ b/frontend/src/pages/Setup.tsx
@@ -65,8 +65,8 @@ const Setup: React.FC = () => {
       await queryClient.invalidateQueries({ queryKey: ['setupStatus'] });
       navigate('/');
     },
-    onError: (err: any) => {
-      setError(err.response?.data?.error || 'Setup failed');
+    onError: (err: Error) => {
+      setError(err.message || 'Setup failed');
     },
   });
 
diff --git a/frontend/src/pages/SystemSettings.tsx b/frontend/src/pages/SystemSettings.tsx
index 05feaf3d..1cbf450a 100644
--- a/frontend/src/pages/SystemSettings.tsx
+++ b/frontend/src/pages/SystemSettings.tsx
@@ -77,7 +77,7 @@ export default function SystemSettings() {
       queryClient.invalidateQueries({ queryKey: ['settings'] })
       toast.success('System settings saved')
     },
-    onError: (error: any) => {
+    onError: (error: Error) => {
       toast.error(`Failed to save settings: ${error.message}`)
     },
   })
diff --git a/frontend/src/pages/Uptime.tsx b/frontend/src/pages/Uptime.tsx
index bdce081f..3d630f4d 100644
--- a/frontend/src/pages/Uptime.tsx
+++ b/frontend/src/pages/Uptime.tsx
@@ -67,7 +67,7 @@ const MonitorCard: React.FC<{ monitor: UptimeMonitor; onEdit: (monitor: UptimeMo
            <div key={`empty-${i}`} className="flex-1 bg-gray-100 dark:bg-gray-700 rounded-sm h-full opacity-50" />
         ))}
 
-        {history?.slice().reverse().map((beat: any, i: number) => (
+        {history?.slice().reverse().map((beat: { status: string; created_at: string; latency: number; message: string }, i: number) => (
           <div
             key={i}
             className={`flex-1 rounded-sm transition-all duration-200 hover:scale-110 ${