# Uptime checks with Healthchecks.io pings

[Healthchecks.io](https://healthchecks.io) alerts you when a ping doesn't arrive on time. Put a ping after a check in a cronservices job: when the check fails, the job stops before the ping, and Healthchecks alerts you by email, SMS, Slack, or any of its integrations.

## Example: alert when your API is down

```json
{
  "name": "API heartbeat",
  "cron": { "expression": "* * * * *" },
  "nodes": [
    { "id": "health", "request": { "method": "GET", "endpoint": "https://api.acme.com/health" } },
    { "id": "ping", "healthchecks_ping": { "ping_url": "https://hc-ping.com/5f3c9a1e-8b2d-4c6f-9e7a-1d2b3c4d5e6f" } }
  ]
}
```

Set the check's period to 1 minute and its grace time to a few minutes, so a single slow response doesn't page anyone.

## Example: watch a nightly job

Ping only when your backup endpoint confirms the last backup is fresh:

```json
{
  "name": "Backup freshness",
  "cron": { "expression": "0 7 * * *", "time_zone": "Europe/Berlin" },
  "nodes": [
    { "id": "fresh", "request": { "method": "GET", "endpoint": "https://backup.example.com/api/fresh?max_age_hours=26", "credential_id": "YOUR_BACKUP_TOKEN_ID" } },
    { "id": "ping", "healthchecks_ping": { "ping_url": "https://hc-ping.com/5f3c9a1e-8b2d-4c6f-9e7a-1d2b3c4d5e6f", "body": "Last backup {{ $.finished_at }}" } }
  ]
}
```

## Set up

Create a check in Healthchecks.io, copy its ping URL into `ping_url`, and set the period to match the job's schedule. Self-hosted Healthchecks servers work too.

## Reference

### Ping a Healthchecks check: `healthchecks_ping`

**Sends** POST the ping URL, or `<ping_url>/fail` or `/start`. **Output** for the next step: The text `OK`.

| Field | Type | Notes |
| --- | --- | --- |
| `ping_url` | string, required | The check’s ping URL, ending in its UUID, on `hc-ping.com` or your own server. |
| `signal` | string | Omit to report success. `fail` reports a failure and `start` starts a timer. |
| `body` | string | A log line stored with the ping, up to 10,000 characters. Placeholders allowed. |