Add Uptime Kuma docs (#39451)

source/_integrations/uptime_kuma.markdown

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+---
+title: Uptime Kuma
+description: Instructions on how to integrate Uptime Kuma with Home Assistant.
+ha_category:
+  - Sensor
+ha_iot_class: Cloud polling
+ha_release: 2025.8
+ha_config_flow: true
+ha_codeowners:
+  - '@tr4nt0r'
+ha_domain: uptime_kuma
+ha_integration_type: integration
+ha_platforms:
+  - sensor
+---
+
+The **Uptime Kuma** {% term integration %} connects Home Assistant with your Uptime Kuma monitoring tool.
+
+## About Uptime Kuma
+
+Uptime Kuma is an open-source, free, and easy-to-use self-hosted monitoring tool used to track the uptime and performance of websites, applications, and other services.
+
+## How you can use this integration
+
+This integration allows you to track the status of your **Uptime Kuma** monitors directly in Home Assistant. You can use these entities in dashboards, automations, and scripts to react to service outages or monitor uptime trends within your smart home setup.
+
+## Prerequisites
+
+To set up the **Uptime Kuma** integration, you need an **API key** and the **URL** of your Uptime Kuma instance (for example: `https://uptime.example.org`).
+
+You can create an API key by logging into your Uptime Kuma instance, navigating to **{% icon "mdi:cog" %} Settings → API Keys** and selecting **{% icon "mdi:plus" %}Add API Key**.
+
+{% include integrations/config_flow.md %}
+
+{% configuration_basic %}
+"URL":
+  description: "Address of your Uptime Kuma instance. Example: `https://uptime.example.com`."
+"Verify SSL certificate":
+  description: "Enable SSL certificate verification for secure connections."
+"API key":
+  description: "An API key to authenticate with your Uptime Kuma instance."
+{% endconfiguration_basic %}
+
+## Sensors
+
+- **Status**: The current status of the monitor. Possible states: *up*, *down*, *pending*, or *maintenance*.
+- **Response time**: Time in milliseconds taken for the last status check.
+- **Certificate expiry**: Number of days remaining before the SSL certificate expires.
+- **Monitor type**: The type of check being performed (e.g., HTTP(s), TCP, ping).
+- **Monitored hostname**: The hostname or IP address being monitored (if applicable).
+- **Monitored port**: The port number used by the monitored service (if applicable).
+- **Monitored URL**: The full URL of the monitored service (if applicable).
+
+## Data updates
+
+This integration retrieves data from your Uptime Kuma instance every 30 seconds.
+
+## Known limitations
+
+- Uptime Kuma's API does not expose unique identifiers for monitors. Because of this, using the same name for multiple monitors will cause only one of them to appear in Home Assistant. Renaming a monitor will result in new entities being created, while the old (stale) entities will remain unless manually removed.
+
+## Removing the integration
+
+This integration can be removed by following these steps:
+
+{% include integrations/remove_device_service.md %}
+
+4. You can now remove the API key used for Home Assistant from Uptime Kuma, unless it is also used by other integrations or applications.