URL Health Monitor β A minimalist WordPress plugin π [Claude Opus 4.5]
Below is a complete, single-file WordPress plugin that does exactly what you described. It's deliberately minimal while still being production-ready.
Features at a glance
- Simple backend UI β a single textarea where you enter URLs (one per line)
- WP-Cron powered β checks every hour by default
- Lightweight storage β results saved in
wp_options, auto-pruned after 365 days - Frontend shortcode β
[url_health_monitor]outputs a clean, responsive status table - Zero dependencies β pure WordPress APIs, no external libraries
The plugin code
Create a file called url-health-monitor.php inside wp-content/plugins/url-health-monitor/ and paste the following:
<?php
/**
* Plugin Name: URL Health Monitor
* Description: A minimalist plugin to monitor URL availability and display results via shortcode.
* Version: 1.0.0
* Author: Your Name
* License: GPL-2.0+
*/
if ( ! defined( 'ABSPATH' ) ) {
exit;
}
class URL_Health_Monitor {
const OPTION_URLS = 'uhm_urls';
const OPTION_RESULTS = 'uhm_results';
const CRON_HOOK = 'uhm_check_urls';
const RETENTION_DAYS = 365;
public function __construct() {
// Admin hooks
add_action( 'admin_menu', [ $this, 'add_admin_menu' ] );
add_action( 'admin_init', [ $this, 'register_settings' ] );
// Cron
add_action( self::CRON_HOOK, [ $this, 'check_all_urls' ] );
add_filter( 'cron_schedules', [ $this, 'add_cron_interval' ] );
// Shortcode
add_shortcode( 'url_health_monitor', [ $this, 'render_shortcode' ] );
// Activation / Deactivation
register_activation_hook( __FILE__, [ $this, 'activate' ] );
register_deactivation_hook( __FILE__, [ $this, 'deactivate' ] );
}
/* -------------------------------------------------------------------------
Activation & Deactivation
------------------------------------------------------------------------- */
public function activate() {
if ( ! wp_next_scheduled( self::CRON_HOOK ) ) {
wp_schedule_event( time(), 'hourly', self::CRON_HOOK );
}
}
public function deactivate() {
wp_clear_scheduled_hook( self::CRON_HOOK );
}
public function add_cron_interval( $schedules ) {
// You can change 'hourly' above to 'uhm_fifteen_minutes' and uncomment below for faster checks.
// $schedules['uhm_fifteen_minutes'] = [
// 'interval' => 900,
// 'display' => __( 'Every 15 Minutes' ),
// ];
return $schedules;
}
/* -------------------------------------------------------------------------
Admin Menu & Settings
------------------------------------------------------------------------- */
public function add_admin_menu() {
add_options_page(
'URL Health Monitor',
'URL Health Monitor',
'manage_options',
'url-health-monitor',
[ $this, 'render_admin_page' ]
);
}
public function register_settings() {
register_setting( 'uhm_settings_group', self::OPTION_URLS, [
'type' => 'string',
'sanitize_callback' => [ $this, 'sanitize_urls' ],
'default' => '',
] );
}
public function sanitize_urls( $input ) {
$lines = explode( "\n", $input );
$clean = [];
foreach ( $lines as $line ) {
$url = esc_url_raw( trim( $line ) );
if ( $url ) {
$clean[] = $url;
}
}
return implode( "\n", $clean );
}
public function render_admin_page() {
if ( ! current_user_can( 'manage_options' ) ) {
return;
}
$urls = get_option( self::OPTION_URLS, '' );
?>
<div class="wrap" style="max-width:720px;">
<h1>π URL Health Monitor</h1>
<form method="post" action="options.php">
<?php settings_fields( 'uhm_settings_group' ); ?>
<p>Enter the URLs you want to monitor, <strong>one per line</strong>:</p>
<textarea name="<?php echo esc_attr( self::OPTION_URLS ); ?>" rows="10" style="width:100%;font-family:monospace;"><?php echo esc_textarea( $urls ); ?></textarea>
<?php submit_button( 'Save URLs' ); ?>
</form>
<hr>
<h2>π Current status</h2>
<?php $this->render_admin_status_table(); ?>
<hr>
<h2>𧩠Shortcode</h2>
<p>Use <code>[url_health_monitor]</code> to display the status table on the frontend.</p>
</div>
<?php
}
private function render_admin_status_table() {
$results = $this->get_results();
if ( empty( $results ) ) {
echo '<p><em>No data yet. Results will appear after the first scheduled check (runs hourly).</em></p>';
echo '<form method="post">';
wp_nonce_field( 'uhm_manual_check', 'uhm_nonce' );
echo '<button type="submit" name="uhm_run_now" class="button">Run check now</button>';
echo '</form>';
if ( isset( $_POST['uhm_run_now'] ) && check_admin_referer( 'uhm_manual_check', 'uhm_nonce' ) ) {
$this->check_all_urls();
echo '<meta http-equiv="refresh" content="0">';
}
return;
}
echo '<form method="post">';
wp_nonce_field( 'uhm_manual_check', 'uhm_nonce' );
echo '<button type="submit" name="uhm_run_now" class="button" style="margin-bottom:12px;">Run check now</button>';
echo '</form>';
if ( isset( $_POST['uhm_run_now'] ) && check_admin_referer( 'uhm_manual_check', 'uhm_nonce' ) ) {
$this->check_all_urls();
echo '<meta http-equiv="refresh" content="0">';
}
$this->render_status_table( $results, false );
}
/* -------------------------------------------------------------------------
URL Checking Logic
------------------------------------------------------------------------- */
public function check_all_urls() {
$raw = get_option( self::OPTION_URLS, '' );
if ( empty( $raw ) ) {
return;
}
$urls = array_filter( array_map( 'trim', explode( "\n", $raw ) ) );
$results = $this->get_results();
$now = current_time( 'timestamp' );
foreach ( $urls as $url ) {
$response = wp_remote_head( $url, [
'timeout' => 15,
'redirection' => 5,
'sslverify' => false,
] );
$status_code = 0;
$is_up = false;
if ( is_wp_error( $response ) ) {
$status_code = 0;
} else {
$status_code = wp_remote_retrieve_response_code( $response );
$is_up = ( $status_code >= 200 && $status_code < 400 );
}
if ( ! isset( $results[ $url ] ) ) {
$results[ $url ] = [ 'history' => [] ];
}
$results[ $url ]['last_checked'] = $now;
$results[ $url ]['status_code'] = $status_code;
$results[ $url ]['is_up'] = $is_up;
$results[ $url ]['history'][] = [
'time' => $now,
'status' => $status_code,
'is_up' => $is_up,
];
}
// Prune old history & orphan URLs
$results = $this->prune_results( $results, $urls );
update_option( self::OPTION_RESULTS, $results );
}
private function prune_results( $results, $current_urls ) {
$cutoff = current_time( 'timestamp' ) - ( self::RETENTION_DAYS * DAY_IN_SECONDS );
foreach ( $results as $url => &$data ) {
// Remove URLs no longer monitored
if ( ! in_array( $url, $current_urls, true ) ) {
unset( $results[ $url ] );
continue;
}
// Remove history entries older than retention period
$data['history'] = array_filter( $data['history'], function ( $entry ) use ( $cutoff ) {
return $entry['time'] >= $cutoff;
} );
$data['history'] = array_values( $data['history'] ); // reindex
}
return $results;
}
private function get_results() {
return get_option( self::OPTION_RESULTS, [] );
}
/* -------------------------------------------------------------------------
Frontend Shortcode
------------------------------------------------------------------------- */
public function render_shortcode( $atts ) {
$results = $this->get_results();
if ( empty( $results ) ) {
return '<p>No monitoring data available yet.</p>';
}
ob_start();
$this->render_status_table( $results, true );
return ob_get_clean();
}
private function render_status_table( $results, $is_frontend ) {
$border_color = '#e0e0e0';
$up_color = '#2e7d32';
$down_color = '#c62828';
?>
<style>
.uhm-table { width:100%; border-collapse:collapse; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, sans-serif; font-size:14px; }
.uhm-table th, .uhm-table td { padding:10px 12px; text-align:left; border-bottom:1px solid <?php echo $border_color; ?>; }
.uhm-table th { background:#f7f7f7; font-weight:600; }
.uhm-table tr:last-child td { border-bottom:none; }
.uhm-status { display:inline-block; padding:3px 10px; border-radius:4px; font-weight:500; font-size:12px; }
.uhm-status.up { background:#e8f5e9; color:<?php echo $up_color; ?>; }
.uhm-status.down { background:#ffebee; color:<?php echo $down_color; ?>; }
.uhm-url { word-break:break-all; }
.uhm-time { color:#666; font-size:12px; }
.uhm-uptime { font-size:12px; color:#555; }
</style>
<table class="uhm-table">
<thead>
<tr>
<th>URL</th>
<th>Status</th>
<th>Uptime (<?php echo self::RETENTION_DAYS; ?>d)</th>
<th>Last checked</th>
</tr>
</thead>
<tbody>
<?php foreach ( $results as $url => $data ) :
$is_up = ! empty( $data['is_up'] );
$status_code = isset( $data['status_code'] ) ? $data['status_code'] : 'β';
$last_time = isset( $data['last_checked'] ) ? human_time_diff( $data['last_checked'], current_time( 'timestamp' ) ) . ' ago' : 'β';
// Calculate uptime %
$history = isset( $data['history'] ) ? $data['history'] : [];
$total = count( $history );
$up_count = 0;
foreach ( $history as $h ) {
if ( ! empty( $h['is_up'] ) ) {
$up_count++;
}
}
$uptime = $total > 0 ? round( ( $up_count / $total ) * 100, 1 ) : 0;
?>
<tr>
<td class="uhm-url"><?php echo esc_html( $url ); ?></td>
<td>
<span class="uhm-status <?php echo $is_up ? 'up' : 'down'; ?>">
<?php echo $is_up ? 'β Online' : 'β Offline'; ?>
</span>
<span style="margin-left:6px;color:#888;font-size:12px;">(<?php echo esc_html( $status_code ); ?>)</span>
</td>
<td class="uhm-uptime"><?php echo esc_html( $uptime ); ?>%</td>
<td class="uhm-time"><?php echo esc_html( $last_time ); ?></td>
</tr>
<?php endforeach; ?>
</tbody>
</table>
<?php
}
}
new URL_Health_Monitor();
How to install
- Create the folder
wp-content/plugins/url-health-monitor/ - Save the code above as
url-health-monitor.phpinside that folder - Activate the plugin via Plugins β Installed Plugins
How to use
-
Configure URLs
Go to Settings β URL Health Monitor. Enter the URLs you want to watch (one per line) and click Save URLs. -
Wait or trigger manually
The plugin checks URLs every hour via WP-Cron. You can also click Run check now in the admin screen to trigger an immediate check. -
Display on the frontend
Insert the shortcode anywhere:[url_health_monitor]It will output a clean status table showing each URL's current state, HTTP status code, uptime percentage, and last-checked time.
Notes on WP-Cron β±οΈ
WordPress cron is visitor-triggered by default β it only fires when someone visits your site. If your site has low traffic, consider adding a real server cron job:
*/15 * * * * curl -s https://yoursite.com/wp-cron.php?doing_wp_cron > /dev/null 2>&1
Then disable the built-in trigger by adding this to wp-config.php:
define( 'DISABLE_WP_CRON', true );
Customisation ideas π¨
| Want to change⦠| Where to look |
|---|---|
| Check interval | Change 'hourly' in activate() to 'twicedaily', 'daily', or register your own schedule via add_cron_interval() |
| Retention period | Adjust RETENTION_DAYS constant |
| Styling | Modify the <style> block inside render_status_table() |
| Timeout / SSL verification | Tweak the wp_remote_head() args in check_all_urls() |
That's it β a clean, minimal URL health monitor in under 300 lines of code. π