diff --git a/homeassistant/components/ista_ecotrend/diagnostics.py b/homeassistant/components/ista_ecotrend/diagnostics.py
new file mode 100644
index 00000000000..4c61c197b5e
--- /dev/null
+++ b/homeassistant/components/ista_ecotrend/diagnostics.py
@@ -0,0 +1,33 @@
+"""Diagnostics platform for ista EcoTrend integration."""
+
+from __future__ import annotations
+
+from typing import Any
+
+from homeassistant.components.diagnostics import async_redact_data
+from homeassistant.core import HomeAssistant
+
+from .coordinator import IstaConfigEntry
+
+TO_REDACT = {
+    "firstName",
+    "lastName",
+    "street",
+    "houseNumber",
+    "documentNumber",
+    "postalCode",
+    "city",
+    "propertyNumber",
+    "idAtCustomerUser",
+}
+
+
+async def async_get_config_entry_diagnostics(
+    hass: HomeAssistant, config_entry: IstaConfigEntry
+) -> dict[str, Any]:
+    """Return diagnostics for a config entry."""
+
+    return {
+        "details": async_redact_data(config_entry.runtime_data.details, TO_REDACT),
+        "data": async_redact_data(config_entry.runtime_data.data, TO_REDACT),
+    }
diff --git a/homeassistant/components/ista_ecotrend/quality_scale.yaml b/homeassistant/components/ista_ecotrend/quality_scale.yaml
index 7e1e6fb92d9..33cf24592b3 100644
--- a/homeassistant/components/ista_ecotrend/quality_scale.yaml
+++ b/homeassistant/components/ista_ecotrend/quality_scale.yaml
@@ -43,7 +43,7 @@ rules:
 
   # Gold
   devices: done
-  diagnostics: todo
+  diagnostics: done
   discovery-update-info:
     status: exempt
     comment: The integration is a web service, there are no discoverable devices.
diff --git a/tests/components/ista_ecotrend/snapshots/test_diagnostics.ambr b/tests/components/ista_ecotrend/snapshots/test_diagnostics.ambr
new file mode 100644
index 00000000000..c9f5e72ae1f
--- /dev/null
+++ b/tests/components/ista_ecotrend/snapshots/test_diagnostics.ambr
@@ -0,0 +1,205 @@
+# serializer version: 1
+# name: test_diagnostics
+  dict({
+    'data': dict({
+      '26e93f1a-c828-11ea-87d0-0242ac130003': dict({
+        'consumptionUnitId': '26e93f1a-c828-11ea-87d0-0242ac130003',
+        'consumptions': list([
+          dict({
+            'date': dict({
+              'month': 5,
+              'year': 2024,
+            }),
+            'readings': list([
+              dict({
+                'additionalValue': '38,0',
+                'type': 'heating',
+                'value': '35',
+              }),
+              dict({
+                'additionalValue': '57,0',
+                'type': 'warmwater',
+                'value': '1,0',
+              }),
+              dict({
+                'type': 'water',
+                'value': '5,0',
+              }),
+            ]),
+          }),
+          dict({
+            'date': dict({
+              'month': 4,
+              'year': 2024,
+            }),
+            'readings': list([
+              dict({
+                'additionalValue': '113,0',
+                'type': 'heating',
+                'value': '104',
+              }),
+              dict({
+                'additionalValue': '61,1',
+                'type': 'warmwater',
+                'value': '1,1',
+              }),
+              dict({
+                'type': 'water',
+                'value': '6,8',
+              }),
+            ]),
+          }),
+        ]),
+        'costs': list([
+          dict({
+            'costsByEnergyType': list([
+              dict({
+                'type': 'heating',
+                'value': 21,
+              }),
+              dict({
+                'type': 'warmwater',
+                'value': 7,
+              }),
+              dict({
+                'type': 'water',
+                'value': 3,
+              }),
+            ]),
+            'date': dict({
+              'month': 5,
+              'year': 2024,
+            }),
+          }),
+          dict({
+            'costsByEnergyType': list([
+              dict({
+                'type': 'heating',
+                'value': 62,
+              }),
+              dict({
+                'type': 'warmwater',
+                'value': 7,
+              }),
+              dict({
+                'type': 'water',
+                'value': 2,
+              }),
+            ]),
+            'date': dict({
+              'month': 4,
+              'year': 2024,
+            }),
+          }),
+        ]),
+      }),
+      'eaf5c5c8-889f-4a3c-b68c-e9a676505762': dict({
+        'consumptionUnitId': 'eaf5c5c8-889f-4a3c-b68c-e9a676505762',
+        'consumptions': list([
+          dict({
+            'date': dict({
+              'month': 5,
+              'year': 2024,
+            }),
+            'readings': list([
+              dict({
+                'additionalValue': '38,0',
+                'type': 'heating',
+                'value': '35',
+              }),
+              dict({
+                'additionalValue': '57,0',
+                'type': 'warmwater',
+                'value': '1,0',
+              }),
+              dict({
+                'type': 'water',
+                'value': '5,0',
+              }),
+            ]),
+          }),
+          dict({
+            'date': dict({
+              'month': 4,
+              'year': 2024,
+            }),
+            'readings': list([
+              dict({
+                'additionalValue': '113,0',
+                'type': 'heating',
+                'value': '104',
+              }),
+              dict({
+                'additionalValue': '61,1',
+                'type': 'warmwater',
+                'value': '1,1',
+              }),
+              dict({
+                'type': 'water',
+                'value': '6,8',
+              }),
+            ]),
+          }),
+        ]),
+        'costs': list([
+          dict({
+            'costsByEnergyType': list([
+              dict({
+                'type': 'heating',
+                'value': 21,
+              }),
+              dict({
+                'type': 'warmwater',
+                'value': 7,
+              }),
+              dict({
+                'type': 'water',
+                'value': 3,
+              }),
+            ]),
+            'date': dict({
+              'month': 5,
+              'year': 2024,
+            }),
+          }),
+          dict({
+            'costsByEnergyType': list([
+              dict({
+                'type': 'heating',
+                'value': 62,
+              }),
+              dict({
+                'type': 'warmwater',
+                'value': 7,
+              }),
+              dict({
+                'type': 'water',
+                'value': 2,
+              }),
+            ]),
+            'date': dict({
+              'month': 4,
+              'year': 2024,
+            }),
+          }),
+        ]),
+      }),
+    }),
+    'details': dict({
+      '26e93f1a-c828-11ea-87d0-0242ac130003': dict({
+        'address': dict({
+          'houseNumber': '**REDACTED**',
+          'street': '**REDACTED**',
+        }),
+        'id': '26e93f1a-c828-11ea-87d0-0242ac130003',
+      }),
+      'eaf5c5c8-889f-4a3c-b68c-e9a676505762': dict({
+        'address': dict({
+          'houseNumber': '**REDACTED**',
+          'street': '**REDACTED**',
+        }),
+        'id': 'eaf5c5c8-889f-4a3c-b68c-e9a676505762',
+      }),
+    }),
+  })
+# ---
diff --git a/tests/components/ista_ecotrend/test_diagnostics.py b/tests/components/ista_ecotrend/test_diagnostics.py
new file mode 100644
index 00000000000..83e28b0b7f8
--- /dev/null
+++ b/tests/components/ista_ecotrend/test_diagnostics.py
@@ -0,0 +1,27 @@
+"""Tests for ista EcoTrend diagnostics platform ."""
+
+import pytest
+from syrupy.assertion import SnapshotAssertion
+
+from homeassistant.core import HomeAssistant
+
+from tests.common import MockConfigEntry
+from tests.components.diagnostics import get_diagnostics_for_config_entry
+from tests.typing import ClientSessionGenerator
+
+
+@pytest.mark.usefixtures("mock_ista")
+async def test_diagnostics(
+    hass: HomeAssistant,
+    hass_client: ClientSessionGenerator,
+    ista_config_entry: MockConfigEntry,
+    snapshot: SnapshotAssertion,
+) -> None:
+    """Test diagnostics."""
+    ista_config_entry.add_to_hass(hass)
+    await hass.config_entries.async_setup(ista_config_entry.entry_id)
+    await hass.async_block_till_done()
+    assert (
+        await get_diagnostics_for_config_entry(hass, hass_client, ista_config_entry)
+        == snapshot
+    )