StaticDelivr vs WP Super Cache

StaticDelivr CDN is a lightweight and powerful plugin designed to improve your WordPress site’s performance. By rewriting theme, plugin, core file resource URLs, optimizing images, and proxying Google Fonts through the StaticDelivr CDN, the plugin ensures faster loading times, reduced server load, better privacy, and an improved user experience. StaticDelivr is a global content delivery network (CDN) that supports delivering assets from various platforms like npm, GitHub, and WordPress. By leveraging geographically distributed servers, StaticDelivr optimizes the delivery of your static assets such as CSS, JavaScript, images, and fonts. Key Features Smart Asset Detection: Automatically detects which themes and plugins are from wordpress.org and only serves those via CDN. Custom themes and plugins are served locally. No configuration needed! Failure Memory System: If a CDN resource fails to load, the plugin remembers and automatically serves it locally for 24 hours. No more repeated failures! Automatic URL Rewriting: Automatically rewrites URLs of enqueued styles, scripts, and core files for themes, plugins, and WordPress itself to use the StaticDelivr CDN. Image Optimization: Automatically optimizes images with compression and modern format conversion (WebP, AVIF). Turn 2MB images into 20KB without quality loss! Google Fonts Privacy Proxy: Serve Google Fonts without tracking (GDPR compliant). A drop-in replacement that strips all user-identifying data and tracking cookies. Automatic Fallback: If a CDN asset fails to load, the plugin automatically falls back to your origin server, ensuring your site never breaks. Localhost Detection: Automatically detects development environments and serves images locally when CDN cannot reach them. Child Theme Support: Intelligently handles child themes by checking parent theme availability on wordpress.org. Separate Controls: Enable or disable assets (CSS/JS), image optimization, and Google Fonts proxy independently. Quality & Format Settings: Customize image compression quality and output format. Verification Dashboard: See exactly which assets are served via CDN vs locally in the admin panel. Failure Statistics: View which resources have failed and are being served locally, with option to clear cache. Compatibility: Works seamlessly with all WordPress themes and plugins — both from wordpress.org and custom/premium sources. Improved Performance: Delivers assets from the StaticDelivr CDN for lightning-fast loading and enhanced user experience. Multi-CDN Support: Leverages multiple CDNs to ensure optimal availability and performance. Free and Open Source: Supports the open-source community by offering free access to a high-performance CDN. Use of Third-Party Service This plugin relies on the StaticDelivr CDN to deliver static assets, including WordPress themes, plugins, core files, optimized images, and Google Fonts. The CDN uses the public WordPress SVN repository to fetch theme/plugin files and serves them through a globally distributed network for faster performance and reduced bandwidth costs. Service Terms of Use: StaticDelivr Terms Privacy Policy: StaticDelivr Privacy Policy How It Works StaticDelivr CDN rewrites your WordPress asset URLs to deliver them through its high-performance network: Smart Asset Detection The plugin automatically verifies which themes and plugins exist on wordpress.org: WordPress.org Assets: Served via StaticDelivr CDN for maximum performance Custom/Premium Assets: Automatically detected and served from your server Child Themes: Parent theme is checked. If the parent is on wordpress.org, assets load via CDN This means the plugin “just works” with any combination of wordpress.org and custom themes/plugins! Failure Memory System (New in 1.7.0!) The plugin learns from CDN failures and automatically adapts: First failure: Fallback fires, failure is recorded Second failure: Resource is blocked from CDN for 24 hours Auto-recovery: After 24 hours, resources are retried automatically Manual reset: Clear the failure cache anytime from settings This ensures that problematic resources (Cloudflare-protected images, auth-gated content, etc.) are handled gracefully without repeated failures. Assets (CSS & JavaScript) Original URL: `https://example.com/wp-content/themes/theme-name/version/style.css` Rewritten CDN URL: `https://cdn.staticdelivr.com/wp/themes/theme-name/version/style.css` This process applies to themes, plugins, and core files: Themes: Original: `https://example.com/wp-content/themes/twentytwentythree/1.0/style.css` CDN: `https://cdn.staticdelivr.com/wp/themes/twentytwentythree/1.0/style.css` Plugins: Original: `https://example.com/wp-content/plugins/woocommerce/assets/js/frontend/woocommerce.min.js` CDN: `https://cdn.staticdelivr.com/wp/plugins/woocommerce/tags/9.3.3/assets/js/frontend/woocommerce.min.js` Core Files: Original: `https://example.com/wp-includes/js/jquery/jquery.min.js` CDN: `https://cdn.staticdelivr.com/wp/core/tags/6.9/wp-includes/js/jquery/jquery.min.js` Images Original: `https://example.com/wp-content/uploads/2024/01/photo.jpg` (2MB) Optimized CDN: `https://cdn.staticdelivr.com/img/images?url=https://example.com/wp-content/uploads/2024/01/photo.jpg&q=80&format=webp` (~20KB) Google Fonts Original CSS: `https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600&display=swap` Privacy Proxy: `https://cdn.staticdelivr.com/gfonts/css2?family=Inter:wght@400;500;600&display=swap` Original Font Files: `https://fonts.gstatic.com/s/inter/v20/example.woff2` Privacy Proxy: `https://cdn.staticdelivr.com/gstatic-fonts/s/inter/v20/example.woff2` This ensures faster delivery through StaticDelivr’s globally distributed network while protecting user privacy. Why Use StaticDelivr? Zero Configuration: Smart detection means it works out of the box with any theme/plugin combination. Self-Healing: Failure memory system automatically adapts to problematic resources. Global Distribution: StaticDelivr serves your assets from a globally distributed network, reducing latency and improving load times. Massive Bandwidth Savings: Offload heavy image delivery to StaticDelivr. Optimized images can be 10-100x smaller! Privacy-First Google Fonts: Serve Google Fonts without tracking cookies — GDPR compliant without additional cookie banners. Works with Custom Themes: Unlike other CDN plugins, StaticDelivr automatically detects custom themes/plugins and serves them locally. Browser Caching Benefits: As an open-source CDN used by many sites, assets served by StaticDelivr are likely already cached in users’ browsers. This enables faster load times when visiting multiple sites using StaticDelivr. Significant Bandwidth Savings: Reduces your site’s bandwidth usage and number of requests significantly by offloading asset delivery to StaticDelivr. Optimized Performance: Ensures assets are delivered quickly, no matter where your users are located. Comprehensive WordPress Support: Includes support for delivering core WordPress files (e.g., those in the `wp-includes` directory) to enhance site speed and reliability. Support for Popular Platforms: Easily integrates with npm, GitHub, WordPress, and Google Fonts. Minimal Configuration: Just enable the features you want and the plugin handles the rest. Development Friendly: Automatically detects localhost and development environments. Translations StaticDelivr CDN is available in the following languages: English (default) Spanish (Español) – es_ES, es_MX French (Français) – fr_FR German (Deutsch) – de_DE Italian (Italiano) – it_IT Portuguese Brazil (Português) – pt_BR Dutch (Nederlands) – nl_NL Japanese (日本語) – ja Chinese Simplified (简体中文) – zh_CN Chinese Traditional (繁體中文) – zh_TW Russian (Русский) – ru_RU Arabic (العربية) – ar Korean (한국어) – ko_KR Turkish (Türkçe) – tr_TR Polish (Polski) – pl_PL Ukrainian (Українська) – uk Czech (Čeština) – cs_CZ Hungarian (Magyar) – hu_HU Romanian (Română) – ro_RO Swedish (Svenska) – sv_SE Danish (Dansk) – da_DK Finnish (Suomi) – fi Hebrew (עברית) – he_IL Persian (فارسی) – fa_IR Hindi (हिन्दी) – hi Vietnamese (Tiếng Việt) – vi Thai (ไทย) – th Indonesian (Bahasa Indonesia) – id_ID Urdu (اردو) – ur Want to help translate StaticDelivr CDN into your language? Visit translate.wordpress.org to contribute! License This plugin is licensed under the GPLv2 or later. See License URI for details.

This plugin generates static html files from your dynamic WordPress blog. After a html file is generated your webserver will serve that file instead of processing the comparatively heavier and more expensive WordPress PHP scripts. The static html files will be served to the vast majority of your users: Users who are not logged in. Users who have not left a comment on your blog. Or users who have not viewed a password protected post. 99% of your visitors will be served static html files. One cached file can be served thousands of times. Other visitors will be served custom cached files tailored to their visit. If they are logged in, or have left comments those details will be displayed and cached for them. The plugin serves cached files in 3 ways (ranked by speed): Expert. The fastest method is by using Apache mod_rewrite (or whatever similar module your web server supports) to serve “supercached” static html files. This completely bypasses PHP and is extremely quick. If your server is hit by a deluge of traffic it is more likely to cope as the requests are “lighter”. This does require the Apache mod_rewrite module (which is probably installed if you have custom permalinks) and a modification of your .htaccess file which is risky and may take down your site if modified incorrectly. Simple. Supercached static files can be served by PHP and this is the recommended way of using the plugin. The plugin will serve a “supercached” file if it exists and it’s almost as fast as the mod_rewrite method. It’s easier to configure as the .htaccess file doesn’t need to be changed. You still need a custom permalink. You can keep portions of your page dynamic in this caching mode. WP-Cache caching. This is mainly used to cache pages for known users, URLs with parameters and feeds. Known users are logged in users, visitors who leave comments or those who should be shown custom per-user data. It’s the most flexible caching method and slightly slower. WP-Cache caching will also cache visits by unknown users if supercaching is disabled. You can have dynamic parts to your page in this mode too. This mode is always enabled but you can disable caching for known users, URLs with parameters, or feeds separately. Set the constant “DISABLE_SUPERCACHE” to 1 in your wp-config.php if you want to only use WP-Cache caching. If you’re not comfortable with editing PHP files then use simple mode. It’s easy to set up and very fast. Recommended Settings Simple caching. Compress pages. Don’t cache pages for known users. Cache rebuild. CDN support. Extra homepage checks. Garbage collection is the act of cleaning up cache files that are out of date and stale. There’s no correct value for the expiry time but a good starting point is 1800 seconds. Consider deleting the contents of the “Rejected User Agents” text box and allow search engines to cache files for you. Preload as many posts as you can and enable “Preload Mode”. Garbage collection of old cached files will be disabled. If you don’t care about sidebar widgets updating often set the preload interval to 2880 minutes (2 days) so all your posts aren’t recached very often. When the preload occurs the cache files for the post being refreshed is deleted and then regenerated. Afterwards a garbage collection of all old files is performed to clean out stale cache files. Even with preload mode enabled cached files will still be deleted when posts are modified or comments made. Development Active development of this plugin is handled on GitHub. Translation of the plugin into different languages is on the translation page. Documentation If you need more information than the following, you can have a look at the wiki or the Developer documentation. Preloading You can generate cached files for the posts, categories and tags of your site by preloading. Preloading will visit each page of your site generating a cached page as it goes along, just like any other visitor to the site. Due to the sequential nature of this function, it can take some time to preload a complete site if there are many posts. To make preloading more effective it can be useful to disable garbage collection so that older cache files are not deleted. This is done by enabling “Preload Mode” in the settings. Be aware however, that pages will go out of date eventually but that updates by submitting comments or editing posts will clear portions of the cache. Garbage Collection Your cache directory fills up over time, which takes up space on your server. If space is limited or billed by capacity, or if you worry that the cached pages of your site will go stale then garbage collection has to be done. Garbage collection happens on a regular basis and deletes old files in the cache directory. On the advanced settings page you can specify: 1. Cache timeout. How long cache files are considered fresh for. After this time they are stale and can be deleted. 2. Scheduler. Setup how often garbage collection should be done. 3. Notification emails. You can be informed on garbage collection job progress. There’s no right or wrong settings for garbage collection. It depends on your own site. If your site gets regular updates, or comments then set the timeout to 1800 seconds, and set the timer to 600 seconds. If your site is mostly static you can disable garbage collection by entering 0 as the timeout, or use a really large timeout value. The cache directory, usually wp-content/cache/ is only for temporary files. Do not ever put important files or symlinks to important files or directories in that directory. They will be deleted if the plugin has write access to them. CDN A Content Delivery Network (CDN) is usually a network of computers situated around the world that will serve the content of your website faster by using servers close to you. Static files like images, Javascript and CSS files can be served through these networks to speed up how fast your site loads. You can also create a “poor man’s CDN” by using a sub domain of your domain to serve static files too. OSSDL CDN off-linker has been integrated into WP Super Cache to provide basic CDN support. It works by rewriting the URLs of files (excluding .php files) in wp-content and wp-includes on your server so they point at a different hostname. Many CDNs support origin pull. This means the CDN will download the file automatically from your server when it’s first requested, and will continue to serve it for a configurable length of time before downloading it again from your server. Configure this on the “CDN” tab of the plugin settings page. This is an advanced technique and requires a basic understanding of how your webserver or CDNs work. Please be sure to clear the file cache after you configure the CDN. REST API There are now REST API endpoints for accessing the settings of this plugin. You’ll need to be authenticated as an admin user with permission to view the settings page to use it. This has not been documented yet but you can find all the code that deals with this in the “rest” directory. Custom Caching It is now possible to hook into the caching process using the add_cacheaction() function. Three hooks are available: ‘wp_cache_get_cookies_values’ – modify the key used by WP Cache. ‘add_cacheaction’ – runs in phase2. Allows a plugin to add WordPress hooks. ‘cache_admin_page’ – runs in the admin page. Use it to modify that page, perhaps by adding new configuration options. There is one regular WordPress filter too. Use the “do_createsupercache” filter to customize the checks made before caching. The filter accepts one parameter. The output of WP-Cache’s wp_cache_get_cookies_values() function. WP Super Cache has its own plugin system, loaded before most of WordPress. Add your own plugin either by putting it in the wp-content/plugins/wp-super-cache-plugins directory, or by calling wpsc_add_plugin( $name ) with the full path to the plugin. The cookies used to identify “known users” can be modified with wpsc_add_cookie( $name ) and wpsc_delete_cookie( $name ). See plugins/searchengine.php as an example. Troubleshooting If things don’t work when you installed the plugin here are a few things to check: Is wp-content writable by the web server? Is there a wp-content/wp-cache-config.php ? If not, copy the file wp-super-cache/wp-cache-config-sample.php to wp-content/wp-cache-config.php and make sure WPCACHEHOME points at the right place. Is there a wp-content/advanced-cache.php ? If not, then you must copy wp-super-cache/advanced-cache.php into wp-content/. You must edit the file and change the path so it points at the wp-super-cache folder. If pages are not cached at all, remove wp-content/advanced-cache.php and recreate it, following the advice above. Make sure the following line is in wp-config.php and it is ABOVE the “require_once(ABSPATH.’wp-settings.php’);” line: define( 'WP_CACHE', true ); Try the Settings->WP Super Cache page again and enable cache. Look in wp-content/cache/supercache/. Are there directories and files there? Anything in your php error_log? If your browser keeps asking you to save the file after the super cache is installed you must disable Super Cache compression. Go to the Settings->WP Super Cache page and disable it there. File locking errors such as “failed to acquire key 0x152b: Permission denied in…” or “Page not cached by WP Super Cache. Could not get mutex lock.” are a sign that you may have to use file locking. Edit wp-content/wp-cache-config.php and uncomment “$use_flock = true” or set $sem_id to a different value. You can also disable file locking from the Admin screen as a last resort. Make sure cache/wp_cache_mutex.lock is writable by the web server if using coarse file locking. The cache folder cannot be put on an NFS or Samba or NAS share. It has to be on a local disk. File locking and deleting expired files will not work properly unless the cache folder is on the local machine. Garbage collection of old cache files won’t work if WordPress can’t find wp-cron.php. Check your access_logs for wp-cron.php entries and that your hostname resolves to the external IP address other servers on the network/Internet use. If old pages are being served to your visitors via the supercache, you may be missing Apache modules (or their equivalents if you don’t use Apache). 3 modules are required: mod_mime, mod_headers and mod_expires. The last two are especially important for making sure browsers load new versions of existing pages on your site. The error message, “WP Super Cache is installed but broken. The path to wp-cache-phase1.php in wp-content/advanced-cache.php must be fixed!” appears at the end of every page. Open the file wp-content/advanced-cache.php in your favourite editor. Is the path to wp-cache-phase1.php correct? This file will normally be in wp-content/plugins/wp-super-cache/. If it is not correct the caching engine will not load. Caching doesn’t work. The timestamp on my blog keeps changing when I reload. Check that the path in your .htaccess rules matches where the supercache directory is. You may have to hardcode it. Try disabling supercache mode. If supercache cache files are generated but not served, check the permissions on all your wp-content/cache/supercache folders (and each of wp-content cache and supercache folders) and wp-content/cache/.htaccess. If your PHP runs as a different user to Apache and permissions are strict Apache may not be able to read the PHP generated cache files. To fix you must add the following line to your wp-config.php (Add it above the WP_CACHE define.) Then clear your cache. umask( 0022 ); If you see garbage in your browser after enabling compression in the plugin, compression may already be enabled in your web server. In Apache you must disable mod_deflate, or in PHP zlib compression may be enabled. You can disable that in three ways. If you have root access, edit your php.ini and find the zlib.output_compression setting and make sure it’s “Off” or add this line to your .htaccess: php_flag zlib.output_compression off If that doesn’t work, add this line to your wp-config.php: ini_set('zlib.output_compression', 0); After uninstalling, your permalinks may break if you remove the WordPress mod_rewrite rules too. Regenerate those rules by visiting the Settings->Permalink page and saving that form again. If your blog refuses to load make sure your wp-config.php is correct. Are you missing an opening or closing PHP tag? Your front page is ok but posts and pages give a 404? Go to Settings->permalinks and click “Save” once you’ve selected a custom permalink structure. You may need to manually update your .htaccess file. If certain characters do not appear correctly on your website your server may not be configured correctly. You need to tell visitors what character set is used. Go to Settings->Reading and copy the ‘Encoding for pages and feeds’ value. Edit the .htaccess file with all your Supercache and WordPress rewrite rules and add this at the top, replacing CHARSET with the copied value. (for example, ‘UTF-8’) AddDefaultCharset CHARSET The error message, “WP Super Cache is installed but broken. The constant WPCACHEHOME must be set in the file wp-config.php and point at the WP Super Cache plugin directory.” appears at the end of every page. You can delete wp-content/advanced-cache.php and reload the plugin settings page or edit wp-config.php and look for WPCACHEHOME and make sure it points at the wp-super-cache folder. This will normally be wp-content/plugins/wp-super-cache/ but you’ll likely need the full path to that file (so it’s easier to let the settings page fix it). If it is not correct the caching engine will not load. If your server is running into trouble because of the number of semaphores used by the plugin it’s because your users are using file locking which is not recommended (but is needed by a small number of users). You can globally disable file locking by defining the constant WPSC_DISABLE_LOCKING, or defining the constant WPSC_REMOVE_SEMAPHORE so that sem_remove() is called after every page is cached but that seems to cause problems for other processes requesting the same semaphore. Best to disable it. Set the variable $htaccess_path in wp-config.php or wp-cache-config.php to the path of your global .htaccess if the plugin is looking for that file in the wrong directory. This might happen if you have WordPress installed in an unusual way.