Query Monitor
by John Blackbourn
A developer panel that exposes slow queries, hooks, HTTP calls and PHP notices on every page you load.
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What Query Monitor does
A developer panel that exposes slow queries, hooks, HTTP calls and PHP notices on every page you load.
It sits in the developer part of a WordPress stack and is sold by John Blackbourn on a free basis. We recommend it in our developer guides because it does that one job well without asking you to rebuild the rest of the site around it.
Every plugin adds work to a page request, so treat this as a decision with a cost. Record a speed test before you install it and run the same test afterwards, on the same page, so you know exactly what it charged you.
Real user ratings
Score
4.9/5
Reviews
469
Active installs
200,000+
Downloads
21.7M
Latest version
4.0.7
Last updated
2026-06-20
These figures come straight from the public WordPress.org plugin directory API for version 4.0.7, not from us. Check them yourself on the WordPress.org listing. Our own editorial score is 4.9/5.
Where Query Monitor ranks elsewhere
Query Monitor does not appear in the published "best of" lists we track from WPBeginner, TechRadar, Kinsta, Themeisle and similar sites. That is not a mark against it - those roundups are short and skew towards the biggest names.
What changed in the latest version
- Confirms support for WordPress 7.0
- Makes improvements to the admin bar menu
- Shows database queries on the timeline even when db.php isn't in place
- Adds more error highlighting for problems with enqueued JavaScript and CSS dependencies
- Adds some back-compat for old versions of the Chrome browser
- Version 4 of Query Monitor adds a new timeline view, and switches from rendering its panels server-side in PHP to efficiently rendering them client-side in Preact. Version 4.0.6 fixes a compatibility issue with the GeneratePress theme. M...
- Ensures closing script tags within data don't break the output
- Adds "Doing it Wrong" data to the timeline view
Release notes are the developer's own words, published on WordPress.org. Read the full changelog
Pros and cons
- Fastest way to find the slow query
- Free with no licence to renew
- Actively maintained and used on production sites we test
- A diagnostic tool, not a fix
- Support is community-led rather than guaranteed
How to use it
- 1Install on a staging copy first if the site takes money.
- 2Work through the setup wizard and connect any external accounts it needs.
- 3Configure the one feature you installed it for, and leave the rest off.
- 4Test the result as a logged-out visitor on both mobile and desktop.
- 5Re-run our speed test to confirm the plugin has not cost you load time.
How it compares
Other developer plugins we recommend, with their rating and pricing model.
| Plugin | Our rating | WordPress.org | Pricing | Best for |
|---|---|---|---|---|
| Query Monitor | 4.9 | 4.9 (469) | Free | Fastest way to find the slow query |
This is the only plugin we currently recommend for this job.
