FAQ
Answers on this page are based on the current plugin code and project documentation.
No. QuantumCache is a query and fragment cache for WordPress. It caches database query results and rendered fragments during PHP execution; it does not store or serve complete HTML responses.
Source: qc_source_of_truth.md §7; quantumcache/readme.txt.
QuantumCache sits below a CDN or full-page cache. If a request is served at the edge or by a page cache, QuantumCache does not run for that request. Its value is on requests that still reach WordPress and PHP.
Pro can also integrate with supported CDNs by emitting cache-tag headers on responses and sending purge signals when tagged content is invalidated.
Source: qc_source_of_truth.md §7; quantumcache/readme.txt; quantumcache-pro/src/Cdn/CdnManager.php.
Free caches the main front-end WP_Query for cacheable requests and can cache common fragments such as post content, query loops, navigation, latest-posts, archives, and classic widget areas.
Pro builds on the same engine and adds WooCommerce-specific fragments and optional logged-in caching controls.
Source: quantumcache/readme.txt; quantumcache/src/Cache/AutoFragments.php; quantumcache-pro/src/WooCommerce/WooModule.php.
QuantumCache supports three store modes: Auto, Redis, and MySQL. In Auto mode it tries Redis first and falls back to MySQL if Redis is not available. The MySQL store uses QuantumCache-owned tables: qc_entries and qc_tagmap.
Free and Pro use the same underlying store selection.
Source: quantumcache/readme.txt; quantumcache/src/Support/StoreFactory.php; quantumcache/src/Store/MySQLStore.php.
No. Redis is recommended for best performance, but it is not required. QuantumCache can run on its MySQL store instead.
Source: quantumcache/readme.txt; quantumcache/src/Support/StoreFactory.php.
In Auto mode, QuantumCache probes Redis and falls back to MySQL when Redis is unavailable.
In forced Redis mode, it tries to connect to Redis and disables that store if the connection fails; it does not automatically switch to MySQL in that mode. If you want automatic fallback, use Auto.
Source: quantumcache/src/Support/StoreFactory.php; quantumcache/src/Store/RedisStore.php.
QuantumCache uses tag-based invalidation. Core cache entries are tagged by post ID, post type, and related taxonomy terms, and the plugin purges on post, term, and certain option changes.
Pro extends invalidation for WooCommerce events including product updates and deletes, stock changes, reviews, term changes, completed orders, and selected catalog settings.
Source: quantumcache/readme.txt; quantumcache/src/Cache/QueryCache.php; quantumcache-pro/src/WooCommerce/InvalidationMap.php.
In Settings → QuantumCache, Free includes Purge Everything, Purge by Tag, and Purge by URL for URLs that resolve to a post ID.
It also includes live storage stats, bounded diagnostics such as key and tag samples, and optional X-QC-* debug headers and HTML debug markers for request-level inspection.
Source: quantumcache/readme.txt; quantumcache/src/Admin/AdminPage.php; quantumcache/src/Support/Helpers.php.
Yes. Free provides wp quantumcache flush and wp quantumcache status. Pro adds wp quantumcache pro:metrics.
Source: quantumcache/readme.txt; quantumcache/src/Cli/CommandRegistrar.php; quantumcache/src/Cli/FlushCommand.php; quantumcache/src/Cli/StatusCommand.php; quantumcache-pro/src/Cli/CommandRegistrar.php; quantumcache-pro/src/Cli/MetricsCommand.php.
Yes, with different levels in Free and Pro.
Free tracks persistent hit, miss, store, and purge counters and exposes them through the admin status view, wp quantumcache status, and the internal metrics API used by the plugin.
Pro can expose those counters through a token-protected Prometheus scrape endpoint and adds admin controls plus a CLI command for viewing or resetting counters.
Source: quantumcache/readme.txt; quantumcache/src/Support/Metrics.php; quantumcache-pro/metrics-endpoint.php; quantumcache-pro/src/Cli/MetricsCommand.php; quantumcache-pro/src/Support/AdminIntegrations.php.
Yes, but Free and Pro are not equivalent here.
Free can cache WooCommerce pages through the core query and fragment cache, but it does not add WooCommerce-specific invalidation or bypass rules.
Pro adds WooCommerce-specific behavior when the Woo module is enabled, including archive handling, Woo fragments, shorter archive TTLs, invalidation hooks, and bypass rules for cart, checkout, account, AJAX, and cart-session cookies.
Source: qc_source_of_truth.md §2, §3; quantumcache-pro/src/WooCommerce/WooModule.php; quantumcache-pro/src/WooCommerce/BypassRules.php; quantumcache-pro/src/WooCommerce/InvalidationMap.php.
Free is anonymous-first and does not cache logged-in traffic by default.
Pro adds optional logged-in caching with a role allowlist, a separate logged-in TTL, and role-aware cache keys. Admin, AJAX, REST, and sensitive account/cart/checkout paths remain excluded.
Source: quantumcache.php; quantumcache/src/Cache/AutoFragments.php; quantumcache/src/Cache/QueryCache.php; quantumcache-pro/src/LoggedIn/LoggedInModule.php.
The inspected Free package declares WordPress 6.0+, PHP 8.0+, and tested up to WordPress 6.9.
The inspected Pro package declares WordPress 6.3+ and PHP 8.1+. The inspected Pro package does not declare a separate Tested up to value in its plugin header.
Source: quantumcache/quantumcache.php; quantumcache/readme.txt; quantumcache-pro/quantumcache-pro.php.
If you need details beyond the inspected code and documentation, contact Support.