Settings reference

A few things that apply everywhere:

• Most tabs have a Save Changes button at the bottom. Nothing you type takes effect until you press it. The Database schedules save the moment you pick one, and the Insights panel saves through its own buttons.
• Saving a tab that changes what a page looks like also clears the page cache, so the next visitor gets the new version rather than a stale snapshot. Changing only the cache lifespan or the filesystem check does not clear anything.
• Settings can be exported and imported as a JSON file from the Import/Export tab (Pro), which is the easiest way to copy a tuned configuration to another site.
• Every time you save, Caching Out also writes a small snapshot of the cache-related settings to disk. That is what lets cached pages be served before WordPress itself loads.
• Settings marked (Pro) come from the Caching Out Pro add-on and need an active licence. Without it they are hidden, and any value already stored for them is kept but ignored.

Anything that can change how a page looks is off until you switch it on. Everything that is safe by default is applied automatically when you activate the plugin, with no configuration.

Performance results vary depending on hosting, theme, plugins and traffic. Benchmark figures are measured on our published test suite and are not a guarantee of results on any specific site.

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Cache

Page caching and the rules for what must never be cached. See Page caching.

Notes

Ignored query parameters, the default list. Since 1.21.17 the list is prefilled with the parameters social networks, ad platforms and campaign links append to a link and that only the browser-side pixels read: fbclid, igshid, igsh, gclid, gbraid, wbraid, dclid, ttclid, msclkid, twclid, yclid, li_fat_id, mc_cid, mc_eid, _ga, _gl, _hsenc, _hsmi and utm_*. Before 1.21.17 the list was empty, so every visitor arriving from Facebook, Instagram or an ad campaign was served an uncached page. There is one list, with one meaning: a parameter on it is removed from the cache lookup and from the cache write, so ?fbclid=abc and ?fbclid=xyz both read the plain page's single cached file and no file is written per value. There is no second list of parameters that produce a different page per value; such a URL is simply not cached. Sites that had already filled the list keep it on update; sites whose list was empty get the defaults. A plugin that puts its own parameter on outbound links registers it with the cachingout_ignored_query_strings filter (append the names to the array it receives); Caching Out rewrites the drop-in's settings file on every settings save and on every plugin activation, and a plugin that registers its names at another moment calls ( new CachingOut_Settings() )->export_runtime_config() once afterwards.

• The built-in safety rules are part of every edition and cannot be turned off: logged-in visitors, session, login and cart cookies, cart, checkout and account pages, wp-admin, the login screen, feeds and sitemaps are never cached. The three "Never cache" lists above are additions to that, not replacements for it.
• Saving this tab clears the whole cache, except when the only change was the lifespan or the filesystem check.
• CACHINGOUT_DISABLE_CACHE in wp-config.php overrides the enable toggle completely. See the kill switch.

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Browser Cache

How long visitors' browsers keep your images, stylesheets and scripts, and whether text files are compressed. See Browser caching.

Notes

• These three write a rules block to your .htaccess file on Apache and LiteSpeed. The file is backed up first, and the block is never written over another plugin's rules.
• On NGINX nothing can be written automatically. Add the equivalent snippet to your server configuration by hand; see server compatibility.
• Deactivating Caching Out never edits .htaccess.

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Preload (Pro)

Fills the cache for you after it is cleared, so the first visitor to each page does not have to wait for it to be built. See Cache preloading.

Notes

• The Preload Now button clears the entire cache and starts again from scratch, whatever the toggle says.
• Preloading is work your server does for itself. On a very small host, a smaller batch size is kinder than a larger one.

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Media

Lazy loading, image dimensions and the priority hint for your main image. See Media optimization.

Notes

• Images and iframes that already carry a loading attribute, or a skip-lazy / no-lazy class or data attribute, are always left alone.
• The main-image priority runs before lazy loading, so an image it prioritises is never lazy-loaded by mistake.

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File Optimization

Minifying, deferring and combining CSS and JavaScript. This is the tab most likely to change how a page looks, so everything on it ships off. See File optimization.

Notes

• Change one setting at a time here, and check the site after each. When something breaks, the exclusion lists are the fix.
• Turning any of these on clears the cache, because cached pages are a snapshot of the optimizations that were on when they were written.
• CACHINGOUT_DISABLE_OPTIMIZATION in wp-config.php switches this whole tab off in one step without changing any of your settings.

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Unused CSS/JS (Pro)

Stops named plugin files from loading on pages that do not use them. This is the only optimization that removes content, so nothing happens until you add a rule and switch it on. See Unused CSS/JS.

Notes

• Preview shows what your rules would remove without saving anything. A rule is never applied until it has been previewed and saved.
• jQuery, the active theme stylesheet, the admin bar, consent, payment and reCAPTCHA files can never be unloaded.
• Device-only rules do nothing until Separate mobile cache is on (Cache tab), because the page cache would otherwise serve one device's page to the other.
• Every rule change is recorded on the Activity page, where it can be undone.

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Database

Cleans up rows WordPress accumulates over time. The free edition runs every cleanup by hand, showing the row count before anything is deleted. See Database cleanup.

The manual operations have no stored setting: each row has Preview and Run. They are Post Revisions, Auto Drafts, Trashed Posts, Spam Comments, Trashed Comments, Expired Transients and All Transients, plus Optimize Tables and Orphaned Metadata with Pro.

Notes

• A schedule saves as soon as you pick it. Choosing anything other than Never both saves the schedule and switches that cleanup on.
• A scheduled cleanup runs unattended, with no preview. Leave an operation on Never until you have previewed it by hand and are happy with what it removes.
• Space saved is an estimate based on average row sizes.
• CACHINGOUT_DISABLE_DATABASE in wp-config.php blocks every cleanup, manual and scheduled.

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CDN (Pro)

Rewrites the addresses of your static files so they are served from a content delivery network. See CDN integration.

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Add-ons (Pro)

Clears third-party caches whenever Caching Out clears its own. See Add-ons.

Notes

• Credentials are stored in your site's database. The safe settings export leaves them out; the second export button includes them, so treat that file as a secret.
• With Pro switched off, a purge clears the local cache only. Nothing is sent to any external service and your stored credentials are untouched.

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Heartbeat

Controls how often WordPress talks to itself in the background, and lets you warm up connections to outside domains.

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Insights

Audits your key pages and explains what to fix. The Page Audit is part of every edition and needs no key or account. See Insights.

Notes

• Without Pro, the tab shows the Page Audit only: no score dial, no baseline, no history and no scheduled re-test.
• Three related values have no on-screen control in this version: the extra pages to track, whether mobile audits run alongside desktop ones (on by default), and scheduled re-tests (off by default, weekly when switched on). They can be set through an imported settings file. See Custom pages.
• Telemetry can be blocked outright with CACHINGOUT_DISABLE_TELEMETRY, whatever the opt-in says.

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AI Assistant (Pro)

A chat tab that already knows your setup: which plugins you run, which settings are on, and what the Page Audit found. It has no settings of its own.

Notes

• The assistant needs an active licence, and it is scoped to Caching Out and your site's configuration. It is not a general-purpose chatbot.
• Your question, a fingerprint of your site (plugin and theme names, PHP version, server type) and, when the Filesystem Check is on, a pass or fail summary of those checks are sent. No page content, visitor data or user information is transmitted.
• What it may see of your change record is controlled by Let the AI Assistant see recent changes on the Cache tab.
• Answers are AI-generated and can be wrong. Test consequential changes on a staging site first.
• When the service cannot be reached, the tab says so before you type.

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License (Pro)

See Licensing for tiers, transfers and renewals.

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Import/Export (Pro)

No stored settings. Two export buttons and one import form. See Import and export.

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Pro

A comparison screen only. It lists what the free edition does, what Pro adds, and where to enter a licence. It saves nothing.

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Other screens

Two screens sit in the Caching Out menu rather than in the settings tabs, and neither has settings of its own:

• Setup Wizard walks through caching, media and optimization choices on a new install and writes them to the tabs above.
• Filesystem Check is a read-only look at every file caching needs: the drop-in, the cache directory and its guards, and the background task wiring. Its Re-run button repeats the activation writes. It is shown or hidden by the Filesystem check toggle on the Cache tab.
• Activity (Pro) lists every change the plugin made, with one-click revert. See Activity.
• On a multisite network, Pro adds network screens for managing sites and applying settings across them. See Multisite.

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Constants for wp-config.php

These are defined in wp-config.php, above the line that says to stop editing. They override the settings screens and cannot be changed from the admin, which is what makes them useful when a site is misbehaving.

define( 'CACHINGOUT_DISABLE_CACHE', true );

Notes

• WP_CACHE is written for you at activation and is not something to set by hand.
• After changing a constant, clear the cache once so nothing built under the old behaviour is still being served.
• Caching Out Pro runs only with the free plugin at 1.22.0 or newer; the two are released as a pair. Upgrade the free plugin first; otherwise Pro refuses to run.