diff --git a/backend/tests/apps/api/internal/mutations/api_key_test.py b/backend/tests/apps/api/internal/mutations/api_key_test.py
index 0d28b8e3d8..2e4715dcc1 100644
--- a/backend/tests/apps/api/internal/mutations/api_key_test.py
+++ b/backend/tests/apps/api/internal/mutations/api_key_test.py
@@ -1,4 +1,4 @@
-from datetime import timedelta
+from datetime import datetime, timedelta
 from unittest.mock import MagicMock, patch
 from uuid import uuid4
 
@@ -56,6 +56,35 @@ def test_create_api_key_success(self, mock_api_key_create, api_key_mutations):
         assert result.api_key == mock_instance
         assert result.raw_key == raw_key
 
+    @patch("apps.api.internal.mutations.api_key.ApiKey.create")
+    @patch("apps.api.internal.mutations.api_key.timezone.now")
+    def test_create_api_key_end_of_day_is_valid(
+        self, mock_now, mock_api_key_create, api_key_mutations
+    ):
+        """Ensure an end-of-day expiry on the current date is accepted."""
+        info = mock_info()
+        user = info.context.request.user
+        fixed_now = datetime(2026, 1, 1, 12, 0, tzinfo=timezone.utc)
+
+        mock_now.return_value = fixed_now
+
+        expires_at = datetime(2026, 1, 1, 23, 59, 59, 999000, tzinfo=timezone.utc)
+
+        mock_instance = MagicMock(spec=ApiKey)
+        mock_api_key_create.return_value = (mock_instance, "raw_key")
+
+        result = api_key_mutations.create_api_key(info, name="Valid Name", expires_at=expires_at)
+
+        mock_api_key_create.assert_called_once_with(
+            user=user, name="Valid Name", expires_at=expires_at
+        )
+
+        assert isinstance(result, CreateApiKeyResult)
+        assert result.ok
+        assert result.code == "SUCCESS"
+        assert result.api_key == mock_instance
+        assert result.raw_key == "raw_key"
+
     @patch("apps.api.internal.mutations.api_key.ApiKey.create", return_value=None)
     def test_create_api_key_limit_reached(self, mock_api_key_create, api_key_mutations):
         """Test creating an API key when the user has reached their active key limit."""
diff --git a/frontend/__tests__/unit/pages/ApiKeysPage.test.tsx b/frontend/__tests__/unit/pages/ApiKeysPage.test.tsx
index 49be7ba55d..d487bdd035 100644
--- a/frontend/__tests__/unit/pages/ApiKeysPage.test.tsx
+++ b/frontend/__tests__/unit/pages/ApiKeysPage.test.tsx
@@ -109,6 +109,16 @@ describe('ApiKeysPage Component', () => {
     }
   }
 
+  const toLocalEndOfDayIso = (date: string) => {
+    const [yearStr, monthStr, dayStr] = date.split('-')
+    const year = Number(yearStr)
+    const month = Number(monthStr)
+    const day = Number(dayStr)
+
+    const endOfDayLocal = new Date(year, month - 1, day, 23, 59, 59, 999)
+    return endOfDayLocal.toISOString()
+  }
+
   beforeEach(() => setupMocks())
   afterEach(() => jest.clearAllMocks())
 
@@ -154,7 +164,7 @@ describe('ApiKeysPage Component', () => {
       fireEvent.click(screen.getByRole('button', { name: /create api key/i }))
 
       const expectedDate = format(addDays(new Date(), 30), 'yyyy-MM-dd')
-      const expectedIso = new Date(`${expectedDate}T00:00:00.000Z`).toISOString()
+      const expectedIso = toLocalEndOfDayIso(expectedDate)
 
       await waitFor(() => {
         expect(mockCreateMutation).toHaveBeenCalledWith({
@@ -176,7 +186,27 @@ describe('ApiKeysPage Component', () => {
         expect(mockCreateMutation).toHaveBeenCalledWith({
           variables: {
             name: 'Custom Expiry Key',
-            expiresAt: new Date('2025-12-31T00:00:00.000Z').toISOString(),
+            expiresAt: toLocalEndOfDayIso('2025-12-31'),
+          },
+        })
+      })
+    })
+
+    test('creates API key for today using end-of-day UTC', async () => {
+      render(<ApiKeysPage />)
+      await openCreateModal()
+
+      const today = format(new Date(), 'yyyy-MM-dd')
+      fillKeyForm('Today Key', today)
+      fireEvent.click(screen.getByRole('button', { name: /create api key/i }))
+
+      const expectedIso = toLocalEndOfDayIso(today)
+
+      await waitFor(() => {
+        expect(mockCreateMutation).toHaveBeenCalledWith({
+          variables: {
+            name: 'Today Key',
+            expiresAt: expectedIso,
           },
         })
       })
@@ -415,7 +445,7 @@ describe('ApiKeysPage Component', () => {
               name: 'third key',
               isRevoked: false,
               createdAt: '2025-07-10T08:17:45.406011+00:00',
-              expiresAt: '2025-12-31T00:00:00+00:00',
+              expiresAt: '2025-12-31T23:59:59.999Z',
             },
           ],
           activeApiKeyCount: 3,
diff --git a/frontend/src/app/settings/api-keys/page.tsx b/frontend/src/app/settings/api-keys/page.tsx
index 94006ba6d8..1d7c59d6e7 100644
--- a/frontend/src/app/settings/api-keys/page.tsx
+++ b/frontend/src/app/settings/api-keys/page.tsx
@@ -20,6 +20,26 @@ import { ApiKeysSkeleton } from 'components/skeletons/ApiKeySkeleton'
 
 const MAX_ACTIVE_KEYS = 3
 
+// Use local end-of-day so selecting "today" remains valid after UTC serialization.
+const toEndOfDayUtcIso = (date: string): string => {
+  const [yearStr, monthStr, dayStr] = date.split('-')
+  const year = Number(yearStr)
+  const month = Number(monthStr)
+  const day = Number(dayStr)
+
+  if (!Number.isFinite(year) || !Number.isFinite(month) || !Number.isFinite(day)) {
+    const fallbackDate = new Date(date)
+    if (Number.isNaN(fallbackDate.getTime())) {
+      return new Date().toISOString()
+    }
+    fallbackDate.setHours(23, 59, 59, 999)
+    return fallbackDate.toISOString()
+  }
+
+  const endOfDayLocal = new Date(year, month - 1, day, 23, 59, 59, 999)
+  return endOfDayLocal.toISOString()
+}
+
 // Content state components
 const ErrorState = () => (
   <div className="rounded-md bg-red-50 p-4 text-red-700 dark:bg-red-900/20 dark:text-red-400">
@@ -184,7 +204,7 @@ export default function Page() {
     }
     const variables: { name: string; expiresAt: string } = {
       name: newKeyName.trim(),
-      expiresAt: new Date(newKeyExpiry).toISOString(),
+      expiresAt: toEndOfDayUtcIso(newKeyExpiry),
     }
     createApiKey({ variables })
   }