Dead-man-switch monitoring for WP-Cron. Get alerted when scheduled events stop firing — uptime monitors do not catch this.

Md Musfiqur Rahman

Accelvia Uptime Monitor

A self-hosted WordPress uptime monitoring plugin with dual-layer architecture, SSL tracking, defacement detection, and multi-channel alerting.

cronheart

WP-Cron is request-driven. On a low-traffic site no requests 
arrive, no events fire, and a scheduled backup can be stalled for 
weeks before anyone notices. Uptime monitors do not catch this — the 
site responds to HTTPS just fine, it just is not running its jobs.
Cronheart turns WP-Cron into a dead-man switch: the plugin pings 
<a href="https://cronheart.com" rel="nofollow ugc">cronheart.com</a> every five minutes and on 
every individual event you register. If the pings stop, cronheart 
alerts you via email, Telegram, Slack, Discord, or a custom webhook.
<h4>What it does</h4>
<ul>
<li>Site heartbeat. A 5-minute custom WP-Cron event whose only job 
is to ping cronheart. Proves WP-Cron itself is alive on this site.</li>
<li>Per-event monitoring. Register any scheduled hook for 
start / success / fail pings with one PHP one-liner: 
 cronheart_monitor( ‘my_nightly_report’, ‘xxxxxxxx-…’ );</li>
<li>PHP fatal-error capture. When a scheduled callback fatals or 
throws, the fail-ping body includes the <code>error_get_last()</code> 
summary — the cronheart dashboard shows the cause without you 
tailing <code>debug.log</code>.</li>
<li>Settings page. A read-only “Monitored events” table at 
Settings → Cronheart shows every hook the plugin is watching and 
where its UUID came from (constant, option, filter).</li>
<li>Monitor picker. Save a cronheart.com API token and the site 
heartbeat field becomes a dropdown of your account’s monitors 
instead of a hand-typed UUID. Entirely optional — without a token 
you paste the UUID as before, and any API hiccup falls back to that 
field. The token is write-only and never leaves wp-admin.</li>
<li>Configuration through <code>wp-config.php</code> constants for production 
(<code>CRONHEART_HEARTBEAT_UUID</code>, <code>CRONHEART_EVENT_<HOOK>_UUID</code>), with 
admin-UI fallback for sites where editing <code>wp-config.php</code> is not 
practical.</li>
</ul>
<h4>Never breaks WP-Cron</h4>
The plugin’s hard contract: a broken cronheart backend, an 
unreachable network, a misbehaving PSR-18 HTTP client — none of 
them may cause WP-Cron to fail. Every network / HTTP error is 
swallowed into a logged warning. If cronheart goes down for a 
day, your <code>wp_schedule_event</code> callbacks still run normally; you 
just stop seeing pings on the dashboard.
<h4>External services</h4>
This plugin sends HTTP requests to <a href="https://cronheart.com" rel="nofollow ugc">cronheart.com</a> 
in two distinct situations. Both are opt-in: without configuration 
the plugin loads and does nothing — no telemetry, no usage 
statistics, no anonymous reports.
1. Monitoring pings (front end / WP-Cron). Sent on every 
scheduled WP-Cron run, but only when you supply a monitor UUID. 
The exact data sent per ping:
<ul>
<li>The per-monitor UUID you configured (path segment).</li>
<li>A short body excerpt — capped at 10 KB — containing either an 
exception summary (for <code>fail</code> pings) or nothing (for <code>start</code> / 
 success / <code>heartbeat</code>).</li>
<li>The plugin / SDK version in a <code>User-Agent</code> header.</li>
</ul>
2. Monitor listing (wp-admin only). When — and only when — you 
save a cronheart.com API token, the Settings → Cronheart page 
calls <code>https://cronheart.com/api/v1/monitors</code> to fetch your monitor 
list for the heartbeat picker. The request carries the token as an 
 Authorization: Bearer header and runs only while a logged-in 
administrator is viewing that settings page — never on the front 
end, during WP-Cron, or in any other context. No token, no request. 
The token is optional; without it you simply paste a monitor UUID by 
hand and this call is never made.
<a href="https://cronheart.com/terms" rel="nofollow ugc">Cronheart.com Terms of Service</a> · 
<a href="https://cronheart.com/privacy" rel="nofollow ugc">Privacy policy</a>
<h4>Open source</h4>
Source code and issue tracker: 
<a href="https://github.com/alexander-po/cronheart-wp" rel="nofollow ugc">github.com/alexander-po/cronheart-wp</a>.
The plugin wraps the 
<a href="https://github.com/alexander-po/cron-monitor-php" rel="nofollow ugc"><code>cron-monitor/php-sdk</code></a> 
PHP package (also open source, MIT-licensed). Both projects are 
maintained independently.

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