Moon SEO

A lightweight, modular WordPress plugin for technical SEO. It prints the SEO tags in <head>, serves an XML sitemap, and outputs structured data (JSON-LD). It works with any theme and does not depend on any other plugin.

Moon SEO does not render anything visible on the front end and loads no front-end CSS or JavaScript.

Features

General

• SEO title and meta description with templates and placeholders ({title}, {site_name}, {tagline}, {separator}, {query}, {term_title}). An empty description is generated from the excerpt or the first paragraph.
• Canonical URL and robots directives, with global presets per page type and per-post overrides. The directives are merged into the robots tag WordPress already prints, so there is never a second one.
• Open Graph and Twitter Card tags, and site verification tags (Google, Bing, Yandex).
• Block editor sidebar with a live preview of the title and description exactly as the front end will print them. Content types without block editor support get a meta box instead; the two are never shown together.
• Optional removal of the category and tag base from URLs (old URLs redirect with a 301), and redirection of attachment pages to their parent.

Sitemap

• /sitemap.xml index, plus one sitemap per content type with pagination (/post-sitemap.xml, /post-sitemap2.xml, and so on).
• Homepage, posts, pages, categories, tags, authors, date archives, and any public custom post type or taxonomy.
• Accurate lastmod only. priority and changefreq are not output because major search engines ignore them.
• Cached, with automatic invalidation when content changes. Excluded categories and post IDs, and posts marked noindex or protected by a password are left out.
• The WordPress core sitemap is turned off and a Sitemap: line is added to the virtual robots.txt.

Schema

• One JSON-LD @graph per page with WebSite, Organization, BreadcrumbList, Article or WebPage, and the primary ImageObject.
• No settings page: everything is derived from the site identity and the post itself.

Requirements

• WordPress 6.9 or later
• PHP 8.0 or later
• Pretty permalinks (not "Plain") are recommended

Installation

1. Download the plugin archive.
2. In WordPress, go to Plugins → Add New → Upload Plugin, choose the archive, and activate it.
3. Open SEO in the admin menu for the General settings and SEO → Sitemap for the sitemap settings.

A fresh install already serves a useful sitemap and meta tags without saving anything.

Run only one SEO plugin at a time. Moon SEO does not detect other SEO plugins, so two of them active together may print duplicate tags.

Extending

Two public filters are the only supported extension points.

moon_seo_supported_post_types decides which post types get per-post SEO fields, title and description templates, and Schema nodes. By default these are post, page, and every other public post type that has an admin UI, except attachment.

add_filter( 'moon_seo_supported_post_types', function ( array $post_types ): array {
    // Treat "docs" as an article.
    $post_types['docs'] = array(
        'content_group' => 'post',
        'schema_node'   => 'article',
    );

    // Leave "event" out entirely.
    unset( $post_types['event'] );

    return $post_types;
} );

moon_seo_module_is_active switches a module off for a request. The module slugs are general, sitemap, and schema.

add_filter( 'moon_seo_module_is_active', function ( bool $active, string $module_slug ): bool {
    return 'schema' === $module_slug ? false : $active;
}, 10, 2 );

Option names, post meta keys, REST routes, and internal classes are not part of the public API.

Known limitations

• Every page of a sitemap type shares the same lastmod in the index.
• The static front page is listed in both the homepage sitemap and the page sitemap.
• Categories or tags hidden from search results in the General settings are still listed in their sitemap. Turn off the matching toggle in the sitemap settings to remove them.
• A parent page that is not public still appears in the breadcrumb trail of its children.
• JSON-LD printed by other plugins or themes is not merged into the Moon SEO graph. Use moon_seo_module_is_active to switch Schema off if another plugin provides it.

Uninstall

Deleting the plugin from the Plugins screen removes its options, per-post SEO fields, sitemap cache, and stored rewrite rules (on every site of a multisite network).

Development

The JavaScript in build/ is compiled from src/ with @wordpress/scripts. build/ is not stored in the repository: run npm ci and npm run build after cloning, or install a release archive. Node 18.12 or later is required.

npm ci
npm run build          # compile src/ into build/
npm run lint           # lint the JavaScript and the CSS
npm run check:version  # the version must match in every file that states it
npm run plugin-zip     # build the release archive
npm run check:release  # verify what the archive contains
npm run verify         # all of the above, in order
npm run makepot        # regenerate languages/moon-seo.pot (requires WP-CLI)
npm run makejson       # JSON translations for the scripts, from the .po files (requires WP-CLI)

PHP is checked with PHP_CodeSniffer and the WordPress Coding Standards (composer install, then vendor/bin/phpcs). phpcs-compat.xml checks compatibility with the minimum PHP version; it needs PHP_CodeSniffer 4 with PHPCompatibility, which the CI workflow (.github/workflows/ci.yml) installs. There is no Composer autoloading at runtime; Composer is only used for development tooling.

To release a new version, change it in the plugin header and in MOON_SEO_VERSION (both in moon-seo.php) and in package.json, then run npm run verify.

License

GPL-2.0-or-later. See LICENSE.