Warmer – Cache Warmer and Cache Preload Crawler

Description

Warmer is a WordPress cache warmer and cache preload crawler that visits your site URLs on a schedule so page cache can be generated before real visitors arrive.

Most caching plugins create cached pages only after a URL is requested. That means the first visitor after a cache purge, cache expiration, deployment, or content update may hit a slower uncached page. Warmer helps solve that cold-cache problem by crawling selected URLs in the background and warming the cache ahead of time.

Use Warmer to warm posts, pages, archives, media attachment pages, and supported custom post types. You control the schedule, URL sources, request delay, timeout behavior, and diagnostics from the WordPress admin.

What Warmer does

  • Warms page cache by visiting selected site URLs
  • Preloads cache on a schedule using WordPress cron
  • Crawls posts, pages, category archives, tag archives, media attachment pages, archives, and supported custom post types
  • Provides manual start and stop controls
  • Shows crawl status, success counts, failure counts, and downloadable logs
  • Includes diagnostics for HTTP requests, URL sources, scheduler status, and server compatibility
  • Supports automation workflows with webhooks and WP-CLI
  • Saves settings automatically with Ajax and top-right confirmation notices
  • Works alongside caching systems that build cache when a page is requested

Why use a cache warmer?

A caching plugin can make cached pages fast, but the cache usually needs to exist first. After a purge or expiration, the first real visitor may be the one who triggers cache generation.

Warmer creates those first visits automatically, helping reduce cold-cache page loads and keeping important URLs ready for visitors.

Warmer is useful after:

  • Cache purges or cache expiration
  • Publishing or updating content
  • Theme, plugin, or deployment changes
  • Low-traffic periods where pages may fall out of cache
  • Scheduled maintenance
  • Landing page, archive, and custom post type updates

URL sources

Choose which parts of your site should be warmed:

  • Posts
  • Pages
  • Category archives
  • Tag archives
  • Media attachment pages
  • Archive pages
  • Supported custom post types

Request controls

Fine-tune cache warming behavior for your hosting environment:

  • Page timeout
  • Connection timeout
  • Request delay
  • Retry attempts
  • User-Agent override
  • Redirect handling
  • SSL certificate verification
  • Manual start and stop controls
  • URL source testing

Start with conservative delay and timeout settings, then adjust based on your server response time, cache behavior, and hosting limits.

Logging and diagnostics

Warmer includes visibility tools so you can understand what happened during each cache warming run:

  • Crawl status tracking
  • Success, failure, redirect, average time, and last-run statistics
  • Structured log rows with status badges
  • Log filters for errors, warnings, success, and redirects
  • Search by URL, status, or message
  • Downloadable logs
  • Clear log history with confirmation
  • System information
  • Source testing
  • Schedule status
  • HTTP request diagnostics

Compatibility

Warmer is cache-plugin agnostic. It works with caching plugins, server caches, reverse proxies, and CDN/page cache layers that generate cache when a URL is visited.

Common setups include:

  • LiteSpeed Cache
  • WP Rocket
  • W3 Total Cache
  • WP Super Cache
  • NGINX FastCGI cache
  • Varnish and reverse proxy caches
  • CDN/page cache layers configured to cache visited pages

Warmer does not replace your caching plugin. It helps your existing cache layer stay warm by requesting the pages you choose.

Developer and automation features

  • WP-CLI support for command-line cache warming workflows
  • Webhook support for deployment and publishing workflows
  • Diagnostics for testing URL sources and scheduler behavior
  • Logs that make cache warming easier to monitor and debug

Best use cases

Warmer is built for site owners, developers, agencies, and performance-focused WordPress teams who want to reduce cold-cache page loads.

It is especially helpful for:

  • Business websites
  • Blogs and publishers
  • WooCommerce product pages and category pages when custom post type warming is enabled
  • Membership and LMS sites with cacheable public content
  • Sites using full-page cache
  • Sites with scheduled cache expiration
  • Sites where important pages should stay fast after cache purges

Screenshots

  • Main settings interface with cache warming controls
  • URL source configuration options
  • Schedule configuration
  • Hooks and triggers for automation workflows
  • Request controls for fine-tuning crawler behavior
  • Detailed logging and monitoring interface
  • Diagnostics tools and system information

Installation

  1. Upload the plugin files to the /wp-content/plugins/warmer directory, or install the plugin through the WordPress Plugins screen.
  2. Activate the plugin through the Plugins screen in WordPress.
  3. Go to Settings > Warmer to configure cache warming.
  4. Choose which URL sources should be included.
  5. Set your schedule, timeout, and request delay settings.
  6. Run a manual cache warming test.
  7. Review logs and diagnostics to confirm that URLs are being warmed correctly.

Recommended setup

  • Start with conservative timeout and delay settings.
  • Test a small set of URLs first.
  • Monitor server load during the first cache warming run.
  • Review logs to find failed, redirected, blocked, or non-cacheable URLs.
  • Adjust the schedule based on how often your cache expires or gets purged.
  • Avoid warming private, account, cart, checkout, or other dynamic pages unless you know they are safely cacheable.

FAQ

What is cache warming?

Cache warming means proactively visiting selected URLs so your cache layer can generate cached pages before real visitors request them.

Is Warmer a caching plugin?

No. Warmer is not a page caching plugin. It works alongside your existing cache plugin, server cache, reverse proxy cache, or CDN cache by visiting URLs that should be cached.

Why use Warmer if I already use a caching plugin?

Many caching systems build cache only after a page is visited. After cache expires or gets purged, the first visitor may experience a slower uncached request. Warmer helps prebuild those cached pages in the background.

Which caching plugins are supported?

Warmer is cache-plugin agnostic and works with caching systems that generate cache when a URL is visited. This includes common setups such as LiteSpeed Cache, WP Rocket, W3 Total Cache, WP Super Cache, NGINX FastCGI cache, Varnish, and compatible CDN/page cache layers.

Does Warmer work with WooCommerce?

Warmer can warm public, cacheable WooCommerce pages such as product pages and product category pages when custom post type support is enabled. Dynamic pages such as cart, checkout, and account pages should usually stay excluded from full-page cache and should not be warmed.

Can I control which URLs are warmed?

Yes. You can choose the URL sources that Warmer should include, such as posts, pages, category archives, tag archives, media attachment pages, archives, and supported custom post types.

How often should cache warming run?

Choose a schedule that matches your cache expiration, publishing frequency, and hosting capacity. For many sites, a daily or twice-daily schedule is a safe starting point. High-change sites may need more frequent warming.

Will cache warming slow down my site?

Warmer is designed to run in the background with configurable request delays and timeouts. Start with conservative settings, monitor server load, then adjust based on your hosting environment.

Can I run cache warming manually?

Yes. Warmer includes manual controls so you can start or stop cache warming from the WordPress admin.

Can developers automate cache warming?

Yes. Warmer includes WP-CLI and webhook support for developer workflows, deployment pipelines, and maintenance routines.

How can I monitor cache warming?

Warmer includes crawl status, success and failure statistics, downloadable logs, clear log history, source testing, schedule status, and diagnostics.

What should I do if some URLs fail?

Check the logs and diagnostics first. Failed URLs may be blocked, redirected, protected, timing out, returning errors, or excluded from caching by your cache plugin or hosting configuration.

Should I warm every URL on my site?

Not always. Start with important public pages such as the home page, landing pages, posts, pages, product pages, and category archives. Avoid private, dynamic, or non-cacheable pages.

Does Warmer improve Core Web Vitals?

Warmer can help reduce cold-cache delays by making sure cached pages exist before visitors arrive. It does not replace good hosting, clean code, image optimization, script optimization, or a proper caching setup.

Where can I get support?

For free plugin support, use the WordPress.org support forum. For premium support, use the support channel provided with your premium license.

Reviews

May 12, 2026
Super easy to get going. Installed it, picked my content types, set a schedule, and that was it. The UI is clean and doesn’t feel bloated like others.
October 19, 2025 3 replies
Does not work out of the box as described for my setup I purchased pro and installed on my dedicated server running latest Wordpress with PHP 8.4.* – 54gb ram, 16 core CPU. Proper solid rig with other advanced setup options. Can not start crawler (unable to connect issue). Crashes website on post publish or edit (critical error white-screen story). wp-cli function not compatible with php 8.4. Appears you need to use php 8.2 ( tried to use it, but above errors continued). This day and age, when you pay for a premium product, you expect speedy support….otherwise you are binned. Zero customer support – even an automated response would be welcomed.
April 23, 2025
Warming cache is an excellent way to increase your cache HIT ratio and ensure visitors hit cache as often as possible after cache expiration or content is updated. We’ve been using the Warmer plugin for a few months now, and after monitoring the CrUX data, we saw a decrease of ~29% in our time-to-first-byte (TTFB) on one of our sites. ⚡ Warmer was the only change that was made during this time period. The developer of Warmer understands how to create an easy to use UI that is fast and lightweight. You do want to be careful not to overuse this feature on shared hosts, but you can choose a less aggressive crawler setting if needed in the plugin. And only warm the cache of your most important content (post types).
Read all 4 reviews

Contributors & Developers

“Warmer – Cache Warmer and Cache Preload Crawler” is open source software. The following people have contributed to this plugin.

Contributors

“Warmer – Cache Warmer and Cache Preload Crawler” has been translated into 2 locales. Thank you to the translators for their contributions.

Translate “Warmer – Cache Warmer and Cache Preload Crawler” into your language.

Interested in development?

Browse the code, check out the SVN repository, or subscribe to the development log by RSS.

Changelog

3.0.1

  • Fixed Composer dependency platform metadata to match the plugin PHP requirement and avoid PHP 8.1 platform checks on supported PHP versions.

3.0.0

  • Major admin experience update
  • Added a new, more modern UI design with improved layout, typography, icons, and visual hierarchy.
  • Added manual include/exclude source links with validation for same-site URLs.
  • Added Ajax autosave for settings, replacing manual Save buttons while keeping top-right save notices.
  • Added a richer Logs interface with summary cards, structured rows, status badges, filters, search, severity colors, download, and clear-log confirmation.
  • Added expanded request controls for connection timeout, page timeout, request delay, retry attempts, redirects, SSL verification, and custom User-Agent handling.
  • Added improved schedule management with schedule status cards, run-now, refresh, and disable actions in the Schedule tab.
  • Moved source testing into the Sources tab and improved diagnostics placement.
  • Added clearer Pro upgrade callouts, icons, URL pool limit messaging, and premium UI states.
  • Added dark mode and broad visual refinements across settings, logs, crawler status, notices, and upgrade elements.
  • Added Japanese, Russian, and Portuguese translations and refreshed existing translations.
  • Refactored the codebase for better organization, maintainability, and extensibility.
  • Tested up to WordPress 7.0

2.0.1

  • Tested up to WordPress 6.8
  • Fixed minor visual bugs

2.0.0

  • New UI improvements
  • Complete code refactoring
  • New automated cache warming features
  • New custom post type support
  • New webhook support
  • New WP-CLI support

1.0.0

  • Initial release with core cache warming functionality
  • Configurable content source selection
  • Automated scheduling options
  • Detailed logging and monitoring
  • Debug and testing tools