A website’s load time is a very important factor for attracting an audience and succeeding as an Internet-based business. Faster loading speeds and shorter website load times improve search engine rankings, increase conversion rates, reduce bounce rates and improve the user experience.

Speed tests are performed to simulate website performance in normal conditions and to provide information which can be used to improve a website’s general performance. There are various online tools for this test, and this article tries to introduce some of the most common among them.

Basic Parameters in Evaluating a Website’s Speed

Online website speed test tools use different parameters for performance analysis, the most important of which are as follows:

  • Load Time: The time required (in milliseconds) to load the webpage completely and display it in the browser.
  • Time to First Byte (TTFB): Time required (in milliseconds) for the browser to receive the first byte of data from the server.
  • Requests: Number of HTTP requests sent from the browser to the server to finish loading the webpage. Some actions that can be taken to reduce the number of these request are as follows:
  • Combining the CSS and JS files
  • Defining JS commands in the main file when they are low in number and not using a separate .js file (inline JS).
  • Using the CSS Sprits method
  • Less use of plug-ins that produce lots of external requests
  • DOMContentLoaded (DCL): The time it takes to load all HTML codes.
  • Time to above-the-fold load: Above the fold is the part of a webpage that fills the browser window without needing to move the navigation bar.
  • First Contentful Paint (FCP): The time the browser takes to render the content. This content may include text, pictures, etc.
  • Page Size: The overall size of content and resources that are displayed on the webpage.
  • Round Trips: Number of round trips necessary to load the webpage. A round trip is completed when the browser sends the HTTP Request to the server and the server sends the Response to the browser.
  • Render-blocking round trips: A subcategory of round trips. Render blocking refers to resources that should be loaded before others.
  • Round Trip Time (RTT): The time it takes to complete a round trip.
  • Render blocking resources: Loading other resources will be blocked until specific resources, such as CSS and JavaScript files, are loaded first. The higher the number of resources, the higher the chance the browser fails in completely loading the webpage. To optimize CSS file delivery, the following should be taken into consideration:
  • Calling CSS Files correctly
  • Reducing the number of CSS files
  • Using CSS files less in general

When do Online Test and Analysis Tools Help?

The following cases are only some of the information that can be obtained from the results of online testing tools:

  • Investigating the Minification of HTML, JS and CSS files
  • Finding large sized pictures that create bottlenecks
  • Detecting render-blocking resources
  • Obtaining the Time to First Byte (TTFB) value
  • Testing total loading time, page size and number of requests
  • Testing performance from various geographic locations
  • Testing rendering speed in different browsers
  • Analyzing HTTP Headers, etc.

Well Known Online Tools for Website Speed Testing

There are four well known tools for testing website speeds, including GTmetrix, WebPage Test, Pingdom and Google Chrome DevTools, explained in an article called “Investigating the TTFB Concept”. Other online website speed test tools are introduced in this section.

1. Google PageSpeed Insights

Google PageSpeed Insights is an online test tool that measures website speeds and ranks it from 0 to 100. Scores higher than 85 in normal mode represent good performance for the website tested. Testing website speeds on both desktop and mobile platforms and providing recommendations after the test for improving performance are this tool’s advantages. This tool helps improve website performance according to Time to above-the-fold load and time to fully load the page.

There is another category in the mobile device test result section called User Experience, which shows the size of the window the page is shown in (viewport configuration) and the size of fonts and elements that the user interacts with (buttons, links, etc.)

2. Think with Google

This tool tests website load speeds on mobile platforms and produces a user friendly report that can be sent to website users.

3. Varvy Pagespeed Optimization

Varvy Pagespeed Optimization is another online tool that produces a report in 5 parts, including CSS delivery, resource diagram, page speed issues found, JavaScript usage, and services used.

4. Uptrends

Upternds is a simple tool that makes it possible to test website speeds from various locations. It is compatible with different browsers on desktop and mobile platforms. Its generated report is divided into waterfall breakdown and domain groups.

5. Dotcom Monitor

dotcom-monitor is a tool for speed testing from over 20 different locations. Its distinguishing feature is the ability to run speed tests from all geographic locations simultaneously.

6. Yellow Lab Tools

Yellow Lab Tools provides lots of information and unique features that other tools don’t, like JavaScript interactions and issues related to code validation. This tool ranks the website according to the following parameters:

  • Page weight
  • Requests
  • DOM
  • Bad JavaScript
  • Bad CSS
  • Server Config

7. Sucuri Load Time Tester

Sucuri Load Time Tester is a fast and easy tool for testing website speeds from various locations. This tool gives websites a rank from A to F. TTFB is an important parameter used by this website for measuring speeds.

8. Pagelocity

This tool gives websites a rank between 0 to 100 according to parameters such as Social, SEO, resources and codes. This website provides more features by creating a free account.