diff --git a/CODEOWNERS b/CODEOWNERS
index 15e56afdd2e..6d5b91f5ef6 100644
--- a/CODEOWNERS
+++ b/CODEOWNERS
@@ -208,6 +208,8 @@ tests/components/dexcom/* @gagebenne
 homeassistant/components/dhcp/* @bdraco
 tests/components/dhcp/* @bdraco
 homeassistant/components/dht/* @thegardenmonkey
+homeassistant/components/diagnostics/* @home-assistant/core
+tests/components/diagnostics/* @home-assistant/core
 homeassistant/components/digital_ocean/* @fabaff
 homeassistant/components/discogs/* @thibmaek
 homeassistant/components/dlna_dmr/* @StevenLooman @chishm
diff --git a/homeassistant/components/default_config/manifest.json b/homeassistant/components/default_config/manifest.json
index 88f86034aea..94f2aa2b9f6 100644
--- a/homeassistant/components/default_config/manifest.json
+++ b/homeassistant/components/default_config/manifest.json
@@ -7,6 +7,7 @@
     "cloud",
     "counter",
     "dhcp",
+    "diagnostics",
     "energy",
     "frontend",
     "history",
diff --git a/homeassistant/components/diagnostics/__init__.py b/homeassistant/components/diagnostics/__init__.py
new file mode 100644
index 00000000000..b2f899b5a89
--- /dev/null
+++ b/homeassistant/components/diagnostics/__init__.py
@@ -0,0 +1,123 @@
+"""The Diagnostics integration."""
+from __future__ import annotations
+
+import json
+import logging
+from typing import Protocol
+
+from aiohttp import web
+import voluptuous as vol
+
+from homeassistant.components import http, websocket_api
+from homeassistant.config_entries import ConfigEntry
+from homeassistant.core import HomeAssistant, callback
+from homeassistant.helpers import integration_platform
+from homeassistant.helpers.json import ExtendedJSONEncoder
+from homeassistant.util.json import (
+    find_paths_unserializable_data,
+    format_unserializable_data,
+)
+
+from .const import DOMAIN
+
+_LOGGER = logging.getLogger(__name__)
+
+
+async def async_setup(hass: HomeAssistant, config: dict) -> bool:
+    """Set up Diagnostics from a config entry."""
+    hass.data[DOMAIN] = {}
+
+    await integration_platform.async_process_integration_platforms(
+        hass, DOMAIN, _register_diagnostics_platform
+    )
+
+    websocket_api.async_register_command(hass, handle_info)
+    hass.http.register_view(DownloadDiagnosticsView)
+
+    return True
+
+
+class DiagnosticsProtocol(Protocol):
+    """Define the format that diagnostics platforms can have."""
+
+    async def async_get_config_entry_diagnostics(
+        self, hass: HomeAssistant, config_entry: ConfigEntry
+    ) -> dict:
+        """Return diagnostics for a config entry."""
+
+
+async def _register_diagnostics_platform(
+    hass: HomeAssistant, integration_domain: str, platform: DiagnosticsProtocol
+):
+    """Register a diagnostics platform."""
+    hass.data[DOMAIN][integration_domain] = {
+        "config_entry": getattr(platform, "async_get_config_entry_diagnostics", None)
+    }
+
+
+@websocket_api.require_admin
+@websocket_api.websocket_command({vol.Required("type"): "diagnostics/list"})
+@callback
+def handle_info(
+    hass: HomeAssistant, connection: websocket_api.ActiveConnection, msg: dict
+):
+    """List all possible diagnostic handlers."""
+    connection.send_result(
+        msg["id"],
+        [
+            {
+                "domain": domain,
+                "handlers": {key: val is not None for key, val in info.items()},
+            }
+            for domain, info in hass.data[DOMAIN].items()
+        ],
+    )
+
+
+class DownloadDiagnosticsView(http.HomeAssistantView):
+    """Download diagnostics view."""
+
+    url = "/api/diagnostics/{d_type}/{d_id}"
+    name = "api:diagnostics"
+
+    async def get(  # pylint: disable=no-self-use
+        self, request: web.Request, d_type: str, d_id: str
+    ) -> web.Response:
+        """Download diagnostics."""
+        if d_type != "config_entry":
+            return web.Response(status=404)
+
+        hass = request.app["hass"]
+        config_entry = hass.config_entries.async_get_entry(d_id)
+
+        if config_entry is None:
+            return web.Response(status=404)
+
+        info = hass.data[DOMAIN].get(config_entry.domain)
+
+        if info is None:
+            return web.Response(status=404)
+
+        if info["config_entry"] is None:
+            return web.Response(status=404)
+
+        data = await info["config_entry"](hass, config_entry)
+
+        try:
+            json_data = json.dumps(data, indent=4, cls=ExtendedJSONEncoder)
+        except TypeError:
+            _LOGGER.error(
+                "Failed to serialize to JSON: %s/%s. Bad data at %s",
+                d_type,
+                d_id,
+                format_unserializable_data(find_paths_unserializable_data(data)),
+            )
+            return web.Response(status=500)
+
+        return web.Response(
+            body=json_data,
+            content_type="application/json",
+            headers={
+                "Content-Disposition": f'attachment; filename="{config_entry.domain}-{config_entry.entry_id}.json"'
+            },
+        )
diff --git a/homeassistant/components/diagnostics/const.py b/homeassistant/components/diagnostics/const.py
new file mode 100644
index 00000000000..91d3dc5211a
--- /dev/null
+++ b/homeassistant/components/diagnostics/const.py
@@ -0,0 +1,3 @@
+"""Constants for the Diagnostics integration."""
+
+DOMAIN = "diagnostics"
diff --git a/homeassistant/components/diagnostics/manifest.json b/homeassistant/components/diagnostics/manifest.json
new file mode 100644
index 00000000000..ad6edf110b0
--- /dev/null
+++ b/homeassistant/components/diagnostics/manifest.json
@@ -0,0 +1,9 @@
+{
+  "domain": "diagnostics",
+  "name": "Diagnostics",
+  "config_flow": false,
+  "documentation": "https://www.home-assistant.io/integrations/diagnostics",
+  "dependencies": ["http"],
+  "codeowners": ["@home-assistant/core"],
+  "quality_scale": "internal"
+}
diff --git a/homeassistant/components/diagnostics/strings.json b/homeassistant/components/diagnostics/strings.json
new file mode 100644
index 00000000000..1409d36b63b
--- /dev/null
+++ b/homeassistant/components/diagnostics/strings.json
@@ -0,0 +1,3 @@
+{
+  "title": "Diagnostics"
+}
diff --git a/homeassistant/components/diagnostics/translations/en.json b/homeassistant/components/diagnostics/translations/en.json
new file mode 100644
index 00000000000..f15fe84c3ed
--- /dev/null
+++ b/homeassistant/components/diagnostics/translations/en.json
@@ -0,0 +1,21 @@
+{
+    "config": {
+        "abort": {
+            "already_configured": "Device is already configured"
+        },
+        "error": {
+            "cannot_connect": "Failed to connect",
+            "invalid_auth": "Invalid authentication",
+            "unknown": "Unexpected error"
+        },
+        "step": {
+            "user": {
+                "data": {
+                    "host": "Host",
+                    "password": "Password",
+                    "username": "Username"
+                }
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/script/hassfest/manifest.py b/script/hassfest/manifest.py
index a0c078e325b..54d4944cf70 100644
--- a/script/hassfest/manifest.py
+++ b/script/hassfest/manifest.py
@@ -52,6 +52,7 @@ NO_IOT_CLASS = [
     "default_config",
     "device_automation",
     "device_tracker",
+    "diagnostics",
     "discovery",
     "downloader",
     "fan",
diff --git a/tests/components/diagnostics/__init__.py b/tests/components/diagnostics/__init__.py
new file mode 100644
index 00000000000..620640cd217
--- /dev/null
+++ b/tests/components/diagnostics/__init__.py
@@ -0,0 +1 @@
+"""Tests for the Diagnostics integration."""
diff --git a/tests/components/diagnostics/test_init.py b/tests/components/diagnostics/test_init.py
new file mode 100644
index 00000000000..5c329b00d8e
--- /dev/null
+++ b/tests/components/diagnostics/test_init.py
@@ -0,0 +1,56 @@
+"""Test the Diagnostics integration."""
+from http import HTTPStatus
+from unittest.mock import AsyncMock, Mock
+
+import pytest
+
+from homeassistant.components.websocket_api.const import TYPE_RESULT
+from homeassistant.setup import async_setup_component
+
+from tests.common import MockConfigEntry, mock_platform
+
+
+@pytest.fixture(autouse=True)
+async def mock_diagnostics_integration(hass):
+    """Mock a diagnostics integration."""
+    hass.config.components.add("fake_integration")
+    mock_platform(
+        hass,
+        "fake_integration.diagnostics",
+        Mock(
+            async_get_config_entry_diagnostics=AsyncMock(
+                return_value={
+                    "hello": "info",
+                }
+            ),
+        ),
+    )
+    assert await async_setup_component(hass, "diagnostics", {})
+
+
+async def test_websocket_info(hass, hass_ws_client):
+    """Test camera_thumbnail websocket command."""
+    client = await hass_ws_client(hass)
+    await client.send_json({"id": 5, "type": "diagnostics/list"})
+
+    msg = await client.receive_json()
+
+    assert msg["id"] == 5
+    assert msg["type"] == TYPE_RESULT
+    assert msg["success"]
+    assert msg["result"] == [
+        {"domain": "fake_integration", "handlers": {"config_entry": True}}
+    ]
+
+
+async def test_download_diagnostics(hass, hass_client):
+    """Test record service."""
+    config_entry = MockConfigEntry(domain="fake_integration")
+    config_entry.add_to_hass(hass)
+
+    client = await hass_client()
+    response = await client.get(
+        f"/api/diagnostics/config_entry/{config_entry.entry_id}"
+    )
+    assert response.status == HTTPStatus.OK
+    assert await response.json() == {"hello": "info"}