Rankmath Plugin Compatibility

Rank Math plugin compatibility

Implement a soft, hook-based compatibility layer that keeps working when Rank Math is absent or a module is disabled. Prefer WordPress and documented Rank Math hooks over internal containers, direct output, or copied plugin logic.

Workflow

1. Identify the content surface: singular CPT, taxonomy archive, virtual route, editor-only field, headless URL, or imported SEO metadata.
2. Confirm whether Rank Math is optional or a declared dependency. Keep it optional unless the product explicitly cannot function without it.
3. Register integration hooks early and idempotently.
4. Make frontend output and editor analysis agree, but do not confuse them: frontend PHP filters do not update the editor score, and editor JavaScript filters do not alter frontend tags.
5. Verify rendered HTML, not only stored meta or callback execution.
6. Test once with Rank Math active and once inactive.

Bootstrap safely

rank_math/loaded fires while the Rank Math plugin file is loading, before its plugins_loaded:14 initialization and before modules load on after_setup_theme:2. Handle both plugin load orders:

function acme_rank_math_boot(): void {
	static $booted = false;
	if ( $booted || ! defined( 'RANK_MATH_VERSION' ) ) {
		return;
	}

	$booted = true;
	add_filter( 'rank_math/frontend/title', 'acme_rank_math_title' );
}

if ( did_action( 'rank_math/loaded' ) ) {
	acme_rank_math_boot();
} else {
	add_action( 'rank_math/loaded', 'acme_rank_math_boot' );
}

Apply these rules:

• Do not call rank_math() before rank_math/loaded.
• Do not assume rank_math/loaded means active modules are instantiated. Check module-dependent classes after after_setup_theme priority 2, or simply register their hooks and let inactive modules leave them unused.
• Use RankMath\Helper::is_module_active( 'rich-snippet' ) for Schema and 'sitemap' for XML sitemaps only when the helper exists. The Schema module ID is not schema.
• Do not instantiate Rank Math frontend, Paper, Schema, or Sitemap classes yourself during normal requests.
• Do not edit Rank Math files or load files from RANK_MATH_PATH manually; its Composer autoloader owns those classes.

Make custom content discoverable

For a normal CPT or taxonomy, fix the WordPress registration before adding SEO overrides:

• Register indexable CPTs as public and publicly_queryable, with stable rewrites and canonical permalinks.
• Register public taxonomy archives so is_taxonomy_viewable() succeeds.
• Ensure singular and archive requests set the main query conditionals correctly. Rank Math chooses its Paper implementation from those conditionals.
• Treat rank_math/excluded_post_types and rank_math/excluded_taxonomies as list filters, despite their names. Preserve the array shape.
• Use rank_math/metabox/add_seo_metabox only for UI visibility. It does not make content indexable.
• Do not force private, capability-protected, duplicate, search-only, or noncanonical objects into Rank Math.

Filter frontend metadata

Use the narrowest output filter and preserve its return type:

Scope every callback to the intended query:

function acme_rank_math_robots( array $robots ): array {
	if ( ! is_singular( 'acme_document' ) || ! acme_is_public_document() ) {
		return $robots;
	}

	$robots['index']  = 'index';
	$robots['follow'] = 'follow';
	return $robots;
}
add_filter( 'rank_math/frontend/robots', 'acme_rank_math_robots' );

Do not append a second <title>, canonical, robots tag, Open Graph block, or JSON-LD script on wp_head. Modify the owner plugin's value instead. Rank Math memoizes Paper values during a request, so register filters before wp/rank_math/head and keep callbacks deterministic. Returning an empty canonical removes its output; do that only for a deliberate no-canonical response.

Register replacement variables

Register variables on the dedicated action. Use a globally unique ID and return, never echo, the replacement:

add_action( 'rank_math/vars/register_extra_replacements', static function (): void {
	rank_math_register_var_replacement(
		'acme_reference',
		[
			'name'        => __( 'Document reference', 'acme' ),
			'description' => __( 'Current document reference.', 'acme' ),
			'variable'    => 'acme_reference',
			'example'     => 'DOC-1042',
		],
		static function ( array $var_args, $object ): string {
			$post_id = $object instanceof \WP_Post ? $object->ID : get_queried_object_id();
			return (string) get_post_meta( $post_id, '_acme_reference', true );
		}
	);
} );

Set 'nocache' => true only for genuinely request-varying values. Do not use a user-specific, random, time-varying, or secret value in public SEO metadata.

Feed custom fields into content analysis

The editor analyzer is separate from frontend metadata. Enqueue only on relevant editing screens with dependencies wp-hooks and rank-math-analyzer, then return plain analyzable text:

wp.hooks.addFilter( 'rank_math_content', 'acme/seo', ( content ) => {
	const field = document.querySelector( '#acme-summary' );
	return field ? `${ content } ${ field.value }` : content;
}, 20 );

On field changes, debounce rankMathEditor.refresh( 'content' ). Never include hidden authorization data, secrets, raw JSON blobs, shortcodes that execute side effects, or unbounded HTML. The official documentation also names rank_math_title, but the distributed 1.0.273 build inspected for this skill did not expose a verifiable wp.hooks.applyFilters( 'rank_math_title', ... ) call. Re-check the installed build before relying on that hook.

Persist metadata only when required

Prefer runtime filters for computed values. For an explicit import or migration, core metadata writes such as update_post_meta( $post_id, 'rank_math_title', $value ) can be appropriate, but:

• validate authorization and object ownership before accepting external values;
• preserve structured types such as the rank_math_robots array;
• distinguish absent, empty, inherited, and intentionally cleared values;
• avoid direct SQL so metadata caches and hooks remain coherent;
• do not read Rank Math metadata and then overwrite it later in the same request after Paper has memoized the old value;
• never overwrite administrator-authored SEO fields on every save unless that ownership contract is explicit.

Headless compatibility

When Rank Math headless support is enabled, GET /wp-json/rankmath/v1/getHead?url=<internal-url> builds the same rank_math/head output after reconstructing the WordPress query. Ensure custom rewrites and query conditionals work in a fresh internal request. Do not expose an alternative unauthenticated URL-fetch proxy; Rank Math validates that the requested URL belongs to the site.

Verification

• Request a representative singular, archive, paginated, noindex, password-protected, and 404 URL.
• Assert exactly one title, description, robots tag, canonical, Open Graph set, and Schema script where applicable.
• Confirm canonical URLs are absolute and agree with sitemap URLs.
• Confirm robots arrays contain keyed directives such as ['index' => 'noindex'], not a numeric list.
• Edit the custom field and verify the analyzer refreshes without changing saved content unexpectedly.
• Disable Rank Math and confirm the host plugin neither fatals nor emits duplicate fallback SEO unless that fallback is intentional.

Cross-references

• Use rankmath-schema-integration for JSON-LD graph entities and Schema.org relationships.
• Use rankmath-sitemap-integration for XML sitemap inclusion, exclusion, providers, and invalidation.
• Use wp-security-audit when metadata or custom editor fields accept request data.

What this skill does not cover

• Rank Math PRO-only APIs unless their source is also available and tested.
• Search ranking guarantees, keyword strategy, or editorial SEO advice.
• Direct modification of Rank Math internals, database tables, or settings UI.

References

• Official documentation: https://rankmath.com/kb/filters-hooks-api-developer/
• Official documentation: https://rankmath.com/kb/content-analysis-api/
• Official documentation: https://rankmath.com/kb/make-theme-rank-math-compatible/
• Verified source paths:
  • rank-math.php
  • includes/frontend/paper/class-paper.php
  • includes/opengraph/
  • includes/replace-variables/class-manager.php
  • includes/template-tags.php
  • includes/rest/class-headless.php
  • assets/admin/js/custom-fields.js