About WebPageTest
WebPageTest is an open-source performance testing tool, primarily maintained by Google. It operates through one or more servers that simulate real users by visiting websites and automatically generating detailed performance reports.
A public version of WebPageTest is freely available, supported by a wide network of test servers — this is the version used in most examples and tutorials. For those who prefer full control, the platform’s source code is available on GitHub, allowing you to host your own private instance on your infrastructure.
WebPageTest’s Key Features:
A public version of WebPageTest is freely available, supported by a wide network of test servers — this is the version used in most examples and tutorials. For those who prefer full control, the platform’s source code is available on GitHub, allowing you to host your own private instance on your infrastructure.
WebPageTest’s Key Features:
- Simulated tests from different locations around the world
- Support for a variety of browsers, including Chrome, Firefox, and Safari
- Analysis of web page rendering and the loading process, including waterfall charts and filmstrips
- Customizable test settings, such as connection speed and screen resolution
- Advanced metrics, including Speed Index, Time to First Byte (TTFB), and First Contentful Paint (FCP)
You can use WebPageTest for free. The service offers a free tier that enables you to run hundreds of tests per month and get detailed results.
Why You Should Use WebPageTest
There are plenty of website performance tools out there—many of them free. But the insights you get can vary a lot depending on which one you use.
Another major plus: WebPageTest presents results in a clear, easy-to-understand format, which is especially helpful if you’re new to performance testing. You’ll also get detailed performance metrics—not just summaries—which we’ll break down for you in the next section. We believe that everyone should use performance testing and monitoring tools, especially after big updates like redesigns or switching hosts. When combined with other strategies, such as using a CDN, regular testing helps ensure your site stays fast and reliable.
Why You Should Use WebPageTest
One of the biggest issues with tools such as WebPageTest is that they throw a lot of information at you after you run a test. This isn’t a problem if you know what metrics to focus on. However, it can be intimidating if you’re using the service for the first time.
When it comes to interpreting results, we suggest you focus on three key areas of WebPageTest reports. The first is the Performance Summary section, which provides an overview of your site’s results. It’ll show you where your site stands in terms of performance, usability, and resiliency:
You can click on the icons below each category to view more information. Every category will include details about the elements that were tested and the results. If there’s an issue with the site, the report will mention what element caused it and provide recommendations on how to fix it:
Once you return to the main report page, scroll down to the Page Performance Metrics section. Here, you’ll find several metrics that show you how long your site takes to load and become functional: If you’re not sure what each of these metrics means, here’s a quick breakdown:
When it comes to interpreting results, we suggest you focus on three key areas of WebPageTest reports. The first is the Performance Summary section, which provides an overview of your site’s results. It’ll show you where your site stands in terms of performance, usability, and resiliency:
You can click on the icons below each category to view more information. Every category will include details about the elements that were tested and the results. If there’s an issue with the site, the report will mention what element caused it and provide recommendations on how to fix it:
Once you return to the main report page, scroll down to the Page Performance Metrics section. Here, you’ll find several metrics that show you how long your site takes to load and become functional: If you’re not sure what each of these metrics means, here’s a quick breakdown:
- Time to First Byte (TTFB). This metric measures how long it takes for the site to respond to the browser’s initial request. Slow servers can take a while to respond, which increases the site’s overall loading time.
- Start render. This tells you how long it takes for the page to start displaying visual elements. The site might be loading in the background, but until users see something, they might not know if the page is working correctly.
- First Contentful Paint (FCP): This is the time it takes for the browser to render the first piece of content on the page. A lower FCP indicates a faster-loading site.
- Speed index. A composite score that represents how quickly the page content is visible to users. The lower the score, the better.
- Largest Contentful Paint (LCP). This metric tells you how long it takes to render the largest element on a page. It’s generally a good indicator of the page’s overall loading time.
- Cumulative Layout Shift (CLS). This score tells you how much the layout of a page “shifts” or changes as it loads. The more it shifts, the poorer the user experience. Zero is the number you should aim for here.
- Total blocking time. With this metric, you can see how long it takes before the page becomes usable. It might be done rendering visually, but the page may be loading scripts in the background, which prevents visitors from using it.
Moving on, the Real-World Usage Metrics section shows an overview of the same metrics compared with recent test data from other users (if it’s available). To get the full picture of your site’s performance, we suggest that you compare these metrics with the previous Page Performance Metrics section.
Ideally, the results of the latter should be similar or better:
Finally, we recommend that you review the waterfall chart, which shows the loading process for each element on the page. This can help you identify specific resources that are causing delays or could be optimized for better performance.
Once you’ve identified areas for improvement, you can make targeted changes to your website, such as optimizing images, minifying CSS and JavaScript files, or implementing caching.
Ideally, the results of the latter should be similar or better:
Finally, we recommend that you review the waterfall chart, which shows the loading process for each element on the page. This can help you identify specific resources that are causing delays or could be optimized for better performance.
Once you’ve identified areas for improvement, you can make targeted changes to your website, such as optimizing images, minifying CSS and JavaScript files, or implementing caching.
Should You Use WebPageTest for Your Business?
If you run a website, regular performance testing is essential to ensure a smooth, fast user experience. While there are many tools available, we recommend WebPageTest—and here’s why.
WebPageTest provides detailed insights into how your site loads, helping you identify bottlenecks and areas for improvement. It’s free to use and allows you to store test data for up to 13 months, making it easy to track performance trends over time.
The tool offers advanced testing options, including tests from different locations, browsers, and connection speeds. This makes it great for getting a realistic view of how your site performs for different users around the world.
However, like any tool, WebPageTest isn’t perfect. Its interface can feel a bit overwhelming at first, especially if you’re new to performance testing. Some features also require a learning curve to fully understand and use effectively.
Still, the depth of data it provides makes it well worth the effort. In the next sections, we’ll walk you through how to use WebPageTest, interpret the results, and make meaningful improvements to your site’s speed.
Let’s dive in.
WebPageTest provides detailed insights into how your site loads, helping you identify bottlenecks and areas for improvement. It’s free to use and allows you to store test data for up to 13 months, making it easy to track performance trends over time.
The tool offers advanced testing options, including tests from different locations, browsers, and connection speeds. This makes it great for getting a realistic view of how your site performs for different users around the world.
However, like any tool, WebPageTest isn’t perfect. Its interface can feel a bit overwhelming at first, especially if you’re new to performance testing. Some features also require a learning curve to fully understand and use effectively.
Still, the depth of data it provides makes it well worth the effort. In the next sections, we’ll walk you through how to use WebPageTest, interpret the results, and make meaningful improvements to your site’s speed.
Let’s dive in.
Summary
Keeping your website running at peak performance requires consistent monitoring. That means running regular speed tests and making ongoing improvements to reduce load times.
There are plenty of tools available to help with performance tracking, but we recommend WebPageTest. It’s free, provides detailed performance insights, and stores your test data for up to 13 months—perfect for spotting trends and tracking long-term improvements.
At Kinsta, we’re all about speed. In fact, many of our customers experience up to a 20% boost in performance just by switching to our hosting. With 37 global data centers and a lightning-fast CDN featuring over 260+ POPs, we’ve built our infrastructure for serious speed.
Ready to level up your site? Kinsta’s Managed WordPress Hosting is built for performance, security, and simplicity. Here’s what you get:
There are plenty of tools available to help with performance tracking, but we recommend WebPageTest. It’s free, provides detailed performance insights, and stores your test data for up to 13 months—perfect for spotting trends and tracking long-term improvements.
At Kinsta, we’re all about speed. In fact, many of our customers experience up to a 20% boost in performance just by switching to our hosting. With 37 global data centers and a lightning-fast CDN featuring over 260+ POPs, we’ve built our infrastructure for serious speed.
Ready to level up your site? Kinsta’s Managed WordPress Hosting is built for performance, security, and simplicity. Here’s what you get:
- A user-friendly MyKinsta dashboard for total control
- Unlimited free migrations handled by our expert team
- 24/7/365 support from WordPress specialists
- Premium infrastructure powered by Google Cloud
- Enterprise-level security with Cloudflare integration
- Global presence with 37 data center locations