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Know the moment your domain is at risk, before your visitors do.

Domain Monitor is a self-contained WordPress plugin that watches your site's domain for the quiet failures that take sites offline: an expired registration, DNS records that drifted, a lapsed TLS certificate, broken email DNS, or a www/apex redirect that stopped working. When everything is healthy you get a calm green light. When something changes, you get a clear, non-alarmist warning while there's still time to act.

No API keys. No paid backend. No third-party account. It runs entirely inside your WordPress install and talks only to the public RDAP, DNS, and HTTP services it needs to check your domains.

What it watches

• Registration and expiry (RDAP): registrar, expiration date, and early warnings as the renewal date approaches.
• DNS records: apex and www A/AAAA, MX, and CNAME, checked with PHP's native resolver and a DNS-over-HTTPS fallback when native lookups aren't available.
• TLS certificate: validity and expiration of the live HTTPS certificate.
• Email DNS: MX and targeted TXT records, so a broken mail setup doesn't slip by unnoticed.
• www / apex policy: confirms your canonical redirect still behaves the way it should.
• Drift: every check is snapshotted, so Domain Monitor can tell you what changed, not just that something looks off.

Quick start

1. Grab the latest domain-monitor-x.y.z.zip from the Releases page.
2. In wp-admin: Plugins → Add New → Upload Plugin, choose the zip, and activate.
3. Done. On activation it detects your site's domain, creates its tables, and schedules a daily check. Open your Dashboard to see the status widget.

On a local or staging site (where the host is localhost), tell it which domain to watch in wp-config.php:

define('DOMAIN_MONITOR_PRIMARY_DOMAIN', 'example.com');

Reading the status

• Green: every check passes and nothing is expiring soon.
• Amber: something benign changed, a lookup had trouble, an expiry window opened, or an issue recently recovered.
• Red: the domain expired, stopped resolving, or the site is unreachable.

Amber lingers for a few days after a problem clears, so a flapping issue doesn't bounce you straight back to green and out of mind.

Beyond the dashboard

• REST API: read-only status under domain-monitor/v1 (GET /status, GET /status/{domain}). Access is gated by the domain_monitor_rest_permission filter if you want to wire up token-based auth.
• WP-CLI: wp domain-monitor ... to run checks and read status from a terminal or your own cron.
• Multisite-aware: a network-activated install monitors the network's primary domain, and uninstall cleans up every site.

For developers

Requirements: PHP 7.4+, WordPress 6.6+.

Local development uses wp-env (Docker):

npm install
npm run wp-env:start
npm run wp-env:composer
npm run test:unit

Or run the suite directly if you have PHP and Composer:

composer install
composer test

The plugin is built test-first. Business logic lives in small, WordPress-free classes that take their collaborators by injection; the WordPress specifics (hooks, $wpdb, wp_remote_get(), cron, options) sit in thin adapters around them. Storage is defined by interfaces with two implementations: an in-memory one for fast tests and a $wpdb one for production. That's why the unit tests run without booting WordPress.

Building a release

bin/build.sh                  # WordPress.org-clean zip (no self-updater)
bin/build.sh --with-updater   # GitHub "dogfood" zip (bundles the self-updater)

The result lands in build/domain-monitor-<version>.zip. The script exports from your latest commit (not the working tree), builds a production autoloader, strips every dev file, and refuses to run on a dirty tree or when the plugin header version and the DOMAIN_MONITOR_VERSION constant disagree.

Pushing a vX.Y.Z tag triggers CI to build the dogfood zip and attach it to a GitHub release. That release is what self-updating installs pull from.

Two distribution channels, and why

• Default build is the artifact bound for the WordPress.org repository: GPL-clean, PHP 7.4, no bundled updater (the repo serves updates itself).
• --with-updater build is for dogfooding straight from GitHub before the WordPress.org listing exists. It bundles plugin-update-checker so installs update from GitHub releases. The plugin only switches the updater on when that library is actually present, so the exact same code is safe in both builds.

License

GPL-2.0-or-later.