404ops Cache Tester

See whether WordPress, PHP, your object cache, page cache, or CDN is serving what you expect.

Find out what each caching layer is doing without changing any of it. Cache Tester is a read-only diagnostic plugin for developers, hosts, and site owners troubleshooting stale pages, inconsistent responses, or a cache that may not be working at all.

What it checks

PHP OPcache status, memory use, cached scripts, hits and misses.
Whether WordPress is using a persistent object cache such as Redis or Memcached.
The cache headers returned by your own front page, including Age, X-Cache and Cf-Cache-Status-style signals, plus cookies that can prevent caching.
Relevant WordPress debug constants, including WP_DEBUG and SCRIPT_DEBUG.

Run a live cache test

One click sends five consecutive AJAX requests and compares their timestamps and random values. Five unique responses mean the endpoint is not being cached; repeated values reveal that a cache somewhere in the stack is replaying a response.

Administrators can also see a small front-end page-generation indicator. If that value does not change after a reload, the page itself is probably coming from cache.

The plugin keeps the last ten test summaries and assembles the current status into a plain-text diagnostic report you can review and copy into a support ticket.

Private by design

Cache Tester only requests your own front page. It contacts no third-party service, does not transmit diagnostic data, creates no cookies, and never changes your cache headers or purges a cache. The front-end indicator is visible only to administrators.

Free, full stop

There is no Pro tier and no hosted service to buy. Every check, the live test, history, and diagnostic report are included in the plugin.