> ## Documentation Index
> Fetch the complete documentation index at: https://docs.still200.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Health-check specification

> The request and response contract for HTTP monitors.

## Endpoint requirements

* **Method:** `GET`
* **Content type:** `application/json`
* **Status code:** `200`
* **Accessibility:** reachable from the public internet
* **Timeout:** responds within 5 seconds

Return `200` even when an internal dependency is unhealthy. Still200 reads dependency health from the JSON body. Network errors, non-200 responses, timeouts, invalid JSON, and invalid response shapes count as failed polls.

## Response fields

| Field                     | Type   | Required | Description                                              |
| ------------------------- | ------ | -------- | -------------------------------------------------------- |
| `service_name`            | string | Yes      | Human-readable service name.                             |
| `checks`                  | object | No       | Map of dependency names to check results. `{}` is valid. |
| `checks[name].latency_ms` | number | No       | Dependency latency in milliseconds.                      |
| `checks[name].error`      | string | No       | Human-readable failure detail.                           |

## Status derivation

| Condition                                | Derived status |
| ---------------------------------------- | -------------- |
| `error` has a value                      | `unhealthy`    |
| No error and `latency_ms` is above 1,000 | `degraded`     |
| Any other valid result                   | `healthy`      |

The worst dependency status becomes the monitor's overall result. A degraded result is recorded but does not open an incident.

## Validate an endpoint

```bash theme={null}
curl -X POST https://api.still200.com/monitors/validate \
  -H 'Content-Type: application/json' \
  -d '{"url":"https://example.com/health"}'
```

A valid dependency-aware response looks like:

```json theme={null}
{
  "service_name": "billing-api",
  "status": "healthy",
  "status_code": 200,
  "checks": {
    "postgres": {
      "status": "healthy",
      "latency_ms": 42.7,
      "error": null
    }
  },
  "error": null
}
```

<Note>
  In the validation response, `checks: {}` means the endpoint explicitly reported no dependency checks. `checks: null` means Still200 could not determine the checks; inspect `error` for the reason.
</Note>