Website speed test tools load a page and show how long it takes and what slows it down, usually with Core Web Vitals and a waterfall of every file. They split, as of Oct 2026, into free one-off testers, tools that repeat lab tests on a schedule, and tools that add real-user monitoring or fix speed for you. Ten follow in no particular order.
A slow page loses visitors before they've read a word, and it's one of the few site problems you can measure in a minute. The trick is knowing which kind of test you're looking at, because a one-off lab test and data from real visitors can tell you different stories.
The ten tools below are listed alphabetically and in no particular order. Each description comes from the tool's own website, as of Oct 2026.
Page speed testers and monitors compared
| Tool | Type | Good for |
|---|---|---|
| Calibre | Performance monitoring with real-user data | Real-user Core Web Vitals and CrUX tracking |
| Catchpoint | Internet performance monitoring | Large-scale synthetic and real-user monitoring |
| GTmetrix | Speed test and monitoring | Detailed test reports and scheduled checks |
| KeyCDN | Speed test from a CDN provider | Testing a page from many locations |
| NitroPack | Speed optimisation service | Fixing speed after you've measured it |
| Pingdom | Website monitoring service | Page speed beside uptime checks |
| Request Metrics | Lab testing and real-user monitoring | Lab tests, real users and SEO scores together |
| Sitespeed.io | Open-source performance tool | Debugging a slow page in detail |
| SpeedCurve | Performance monitoring platform | Linking speed to business outcomes |
| Uptrends | Free speed test from a monitoring company | A snapshot with a waterfall report |
Ten tools for testing how fast your site loads
Calibre
Best for: Teams wanting to collect Core Web Vitals from real browser sessions and track Google's CrUX data for every site they monitor, plus scheduled lab checks.
Catchpoint
Best for: Larger organisations wanting synthetic monitoring, real user monitoring and session replay across websites, apps and APIs, with an instant website test to start.
GTmetrix
Best for: Website owners who want a detailed breakdown of how a page loads, test locations around the world and scheduled monitoring with alerts.
KeyCDN
Best for: Anyone wanting a quick full page speed test from 10 locations around the world, on a CDN provider's tools page.
NitroPack
Best for: Site owners who've already tested and want a service that handles caching plus image, CSS and JS optimisation to pass Core Web Vitals.
Pingdom
Best for: Businesses wanting page speed analysis alongside uptime, transaction monitoring and alerts, combining synthetic and real user monitoring.
Request Metrics
Best for: Developers wanting automatic Lighthouse lab testing, real user monitoring and Google SEO scores in one place, with self-host options on enterprise plans.
Sitespeed.io
Best for: Developers who want an open source tool that produces a report with Core Web Vitals, a loading video and a HAR waterfall, or runs every hour.
SpeedCurve
Best for: Teams wanting lab-based synthetic testing and real user monitoring in one place, with A/B tests that link speed improvements to business outcomes.
Uptrends
Best for: Anyone wanting a free snapshot of how desktop or mobile users experience a page, with PageSpeed Insights results and a waterfall report.
One-off test, repeat lab testing or real-user data?
The tool pages show three kinds of help. KeyCDN's page is a full page speed test that can run from 10 different locations around the world, Uptrends offers a website speed test, and GTmetrix says test, monitor and optimise web performance. Sitespeed.io gives you an HTML report with Core Web Vitals, a video of the page loading and the HAR waterfall.
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Then there's real-user data. Calibre collects Core Web Vitals from real browser sessions, Request Metrics combines automatic lab testing and real user monitoring, and Pingdom lists uptime monitoring alongside page speed. SpeedCurve is now part of the Embrace family, and Catchpoint lists WebPageTest among its products. NitroPack is different again: it says pass Core Web Vitals and cut load times, so it's an optimiser rather than only a tester.
Lab tests and real-user data, explained
- Lab tests. A tool loads your page from a test server under set conditions. That's ideal for spotting what's slow and checking a fix, but it's one visit, not your audience.
- Real-user monitoring. A small script measures how fast pages load for your real visitors, on their own devices and connections.
- Core Web Vitals. Google's measures of loading, responsiveness and visual stability. Several tools here report them, and some also show Google's own data from Chrome users.
- Waterfall. A chart of every file the page loads and how long each one took. It's where you'll find the heavy image or the slow script.
- Test location. Testing from somewhere close to your visitors gives a truer picture than testing from the other side of the world.
Before and after a site change: what to run
- Test your key pages before you change anything, and save the reports.
- Test from a location near most of your visitors, on mobile and desktop.
- Run each test more than once, because a single result can be noisy.
- Make the change, then test the same pages the same way.
- Compare the waterfalls, not just the headline score.
- If you have real-user monitoring, watch it for a few weeks after the change.
Speed is one part of technical SEO. My guide to technical SEO for beginners covers the rest.
Do you make website speed testing or performance monitoring software? Tool makers can ask to be considered for a featured place on this list.
My plain advice on testing site speed
For most small business sites, a free one-off tester is where to start: run it on your home page and your busiest pages, then fix what the waterfall shows. If you change your site often, or you run a shop where every second counts, move up to scheduled lab tests. Add real-user monitoring when you want to know what your visitors experience, not just a test server. And if you'd rather someone else did the fixing, an optimisation service is a separate decision from testing.
Using a CDN to speed things up? My comparison of AWS CloudFront vs BunnyCDN helps you choose.
Want your tool on this list? Featured spots and reviews here are paid partnerships. Here's how to partner with me.
Frequently asked questions
What does a website speed test measure?
It loads a page and records how long it takes, usually with Core Web Vitals, a total load time and a waterfall showing every file the page requested.
Why do speed test tools give different results?
They test from different locations, devices and connections, and each run varies a little. Compare results from the same tool and settings over time.
What's the difference between lab data and field data?
Lab data comes from a test under set conditions. Field data, or real-user monitoring, comes from your visitors' own devices and connections.
How often should I test my website's speed?
Test before and after any change to your site, and on a schedule if you update it often. Real-user monitoring runs all the time.
Is a speed test tool the same as a speed optimisation service?
No. A tester measures speed and shows problems. An optimisation service makes changes, like caching and image optimisation, to fix them.
Does page speed matter for SEO?
Google includes Core Web Vitals in its page experience guidance, so it's worth keeping an eye on. Speed alone won't rank a page that doesn't answer the search, though.
