The short version: Use it to measure how quickly your website loads from a variety of server locations.

The Pingdom Website Speed Test may be the most popular website speed test on the web. It’s easy to use, easy to understand, and provides actionable information you can use to improve the performance of your website.

This test loads your website using a real Google Chrome web browser to replicate what a real user experiences when loading the website. The test results include a detailed waterfall chart and a variety of data snapshots you can use to understand what’s going on when your site is served to a web browser. Pingdom also provides recommendations on best practices you might want to implement to speed things up.

Pingdom’s test results are detailed, yet presented in a concise format with actionable recommendations. That makes Pingdom a long-standing webmaster favorite when it comes to testing website speed.

The short version: Get a list of recommendations from Google of how to optimize the delivery of your website.

If any test is more popular than Pingdom Website Speed Test, it’s Google PageSpeed Insights. One thing that makes Google PageSpeed Insights popular is that provides insights into what Google thinks your website visitors think about your website’s performance.

Who doesn’t want to know what Google thinks about their website, am I right?

What PageSpeed Insights does is fetch your site twice: once as a desktop user and a second time as a mobile user. It then grades the performance of your website based on ten performance metrics.

Your goal, according to Google, should be to achieve a score of 85 or higher on both the mobile and desktop versions of the test. However, it’s important to remember that this is a measure of what Google thinks. As a result, from time to time you’ll see someone criticising PageSpeed Insights, usually because PageSpeed Insights doesn’t actually grade a site based on speed and seems to prioritize performance over user experience — an accusation Google has acknowledged does have some validity.

The truth is you can have a slow website that scores higher when tested with PageSpeed Insights than a blazing fast site. However, your users care a lot more about how quickly your website loads than whether you load jQuery in the site header or footer.

So, should you avoid PageSpeed Insights entirely? Hardly. Instead, use PageSpeed Insights as a tool that can tell you specific things about your website, such as:

• Which CSS and JavaScript files are in a render-blocking position?
• Is your browser caching plugin working the way you think it is?
• What are some specific things you can work on to try and improve website speed?

Just don’t chase a perfect PageSpeed Insights score. Instead, use the tool to identify and fix problem areas, and then test website speed with a tool that actually tests speed, such as Pingdom or GTMetrix.

The short version: Get recommendations for improving website delivery by comparing the site to Yahoo’s rules for high-performance websites.

YSlow is an open-source tool you can use to analyze a website and compare it to Yahoo’s rules for high-performance websites. The results of the test are presented as a checklist of recommendations for improving site performance.

What YSlow doesn’t do is actually measure page load speed. Instead, think of YSlow as being the same sort of tool as Google PageSpeed Insights: a measure of how well your site has been optimized for delivery.

There are many different ways to use YSlow. However, there are two really easy ways: run a GTMetrix test and select the YSlow tab from the results dashboard, or install the Chrome Browser Extension and run the test inside of Google Chrome.

The short version: Imagine Google PageSpeed, YSlow, and a website speed test that rivals Pingdom all rolled into one easy-to-use test dashboard.

The GTMetrix website speed test produces results that look a lot like what you get from a Pingdom Website Speed Test. However, in addition to the website speed test, GTMetrix runs your site through Google PageSpeed Insights and YSlow tests and reports the results of all three tests in the GTMetrix dashboard.

If you don’t sign up for an account, the website speed test will be run from Vancouver, Canada. However, signing up for a free account will give you access to seven different testing locations and the ability to test your site using a variety of browsers and throttled connection speeds to approximate the performance a real user would experience.

GTMetrix results rank highly for convenience and comprehensiveness. If you’re only going to use one testing service, GTMetrix might be the best choice.

The short version: See how your website’s server responds when 25 virtual users simultaneously access your website.

Load Impact is unlike any other test on this list. What this test does is measure server performance while multiple virtual users browse your site simultaneously. The test takes about 5 minutes and peaks with 25 simultaneous virtual users.

The test is designed to help you answer the question: Can my site’s server handle a load of multiple simultaneous users without slowing down?

This test is a great tool you can use to make sure that the server hosting your website isn’t overloaded. However, your website doesn’t have to be all that popular to attract more than 25 simultaneous users and you might want to run a load test with a larger number of virtual users. If you need to do that, Load Impact can send hundreds or  even thousands of simultaneous virtual users to your site, but you’ll have to sign up for a monthly plan first.

The short version: Find out how fast your website loads over real consumer internet connections around the world.

WebPageTest.org is an open-source website speed platform originally developed by AOL and later taken over by Google in conjunction with many additional partners (including WordPress.com). As an open-source platform, anyone can see the code on GitHub, download it, and even host their own instance of the testing platform.

WebPageTest.org tests website load speed using real consumer connection speeds. The results demonstrate how your site will perform for a user using an average connection speed. As a result, you can expect your site to test a tick or two slower at WebPageTest.org than at Pingdom or GTMetrix. Think of the results as representing “real world” performance rather than the “ideal environment” results you get from Pingdom or GTMetrix.

Pingdom and GTMetrix tell you how fast your website can load. WebPageTest.org tells you how fast your website actually loads for real consumers.

One really nice feature you get at WebPageTest.org is the ability to test your site using more than 30 different browsers from more than 15 different locations. However, some locations can only be used to test load speed with one or two browsers.

Results presented by WebPageTest.org include most of the same information you get from a Pingdom or GTMetrix speed test, albeit in greater detail and with less emphasis placed on providing a user-friendly experience. The site appears to have been designed for knowledgeable developers and webmasters and not for average casual users.

The short version: Test once and find out how fast your website loads at 24 different locations around the world.

Dotcom-Tools is a suite of free website performance testing tools from Dotcom-Monitor. Here you’ll find tools for testing website speed, server performance, DNS blacklisting, network tracing, and a lot more.

The Website Speed Test loads a webpage from 24 different locations around the globe. The test provides a snapshot of performance metrics from each location including load speed, a waterfall chart, and a summary of any errors encountered during the testing process. In addition, the test can be run using a variety of browsers including Chrome, Firefox, various flavors of Internet Explorer, and several different mobile browsers.

Dotcom-Monitor’s Website Speed Test has noteworthy features unparalleled by other free website testing platforms:

• This tool tests from more locations simultaneously than any other tool on this list.
• The list of test locations includes hard-to-test locations such as China.
• The test results identify the slowest loading resources so you can target these resources for improved performance.

The short version: Get a detailed timed waterfall chart for more than 35 different test locations.

Uptrends Website Speed Test is a simple website speed test that produces a timed waterfall chart of site load speed from any one of more than 35 different test locations. If you want to test website performance from multiple locations, you’ll need to rerun the test manually from each location.

There isn’t really anything in the test results that isn’t provided by the other speed testing services like Pingdom, Dotcom-Monitor, GTMetrix, and WebPageTest.org. However, with more than 35 available test locations, if you need to test performance from a specific location that isn’t covered by another service, check the list of available locations to see if Uptrends offers a test location closer to your audience’s location.