GTmetrix Performance Blog

News, updates and guides on GTmetrix and general web performance

Developer Toolkit Released

Updated March 13th, 2018Added Custom Connection Speeds.

We’re excited to announce the release of our Developer Toolkit!

GTmetrix has a ton of great features available in our Basic account (Sign up if you haven’t yet – it’s free!) – but for those who wanted more advanced insights, we’ve listened to your feedback and created the Developer Toolkit – a bundle of features that can help you get the most out of GTmetrix.

We’re including the Developer Toolkit in our Bronze, Silver and Gold plans, and also offering it as an add-on to PRO custom plans.

Read on to discover what’s included:


Simulate Device

See how your website could display and load on a simulated device. We’ve pre-selected combinations of user agents, screen resolutions, and device pixel ratios that best represent popular devices.

Now you can test your page’s responsive performance on simulated iPhones, iPads, Android phones, tablets and more.

Select from over 20 popular phones and tablets to simulate your page load on.


Be sure to analyze your site with a wide variety of devices to ensure consistent performance for any and all your visitors.

Monitoring and API access is also available for Simulated Devices in our 7 global test regions.

Read more about How to Simulate a Device with GTmetrix.

*Hardware performance is not emulated. Actual loading behaviour may differ on actual device. Learn more here


User Agent Override

Enter your own User Agent (UA) string for GTmetrix to present to your server. This will automatically populate depending on the chosen Browser Options or Simulated Devices.

Advanced users can choose to override the User Agent for our Browser Options – however you cannot change the UA string if you’ve selected to test with a Simulated Device.


Screen Resolution and Device Pixel Ratio (DPR)

The Developer Toolkit allows you to select from a list of the most common screen resolutions for GTmetrix to load your page in.

Choose from a variety of common screen resolutions to perform your GTmetrix test with. Toggle landscape or portrait too.


In addition, you can also input your own Device Pixel Ratio (DPR) – or dots per pixel (dppx) – to ensure an accurate display. Orientation can also be toggled to portrait or landscape mode.

Responsive sites may trigger different layouts/assets with different screen sizes.


Responsive designs will benefit the most from tests with varying screen resolutions, so be sure to test out your site in different resolutions to ensure it’s optimized across all – or choose which devices matter to you most with our Simulate Device feature.

Read more about Screen Resolution and Device Pixel Ratio.


DNS Override

Great for development and staging sites, analysis for before/after server migration, etc. Input your own host and IP address for GTmetrix to use when analyzing your page.

DNS Override now supported.


Note: Sites using https:// and SSL will still require the newly pointed server to have their SSL certificate properly set up, or GTmetrix will be unable to analyze.

Read more about How to Override your DNS with GTmetrix.


Analysis Presets

You can now save all of your Analysis Options as a preset for faster and more convenient testing.

Save your Analysis Options into a preset for convenient testing.


Analysis Presets are accessible in the Analysis Options dropdown on the Dashboard for quick access to your preferred test settings.

Dashboard Analyze Button now has a dropdown for presets.


For even more convenience, Analysis Presets are also available on the Dashboard Analyze button as a dropdown. Just enter a URL in the analysis field and select a preset from the dropdown to immediately test with your desired options.

Read more about How to use Presets with GTmetrix.

And more coming!

Recent updates:

  • March 13th, 2018 – Added Custom Connections to Developer Toolkit. Create a custom speed for GTmetrix to load your site with and better represent your user’s experience. Read more here.

We plan on adding more features and functionality to the Developer Toolkit in the future – keep up to date by following us on Twitter or Facebook!


Optimize your site for all types of users with the Developer Toolkit

GTmetrix Developer Toolkit

The Developer toolkit is included in Bronze, Silver and Gold plans, or you can get it as add-on to PRO Custom plans.

Learn more about the Developer Toolkit »

As a PRO user, you’ll get an enhanced GTmetrix experience with: Priority access for tests, More monitored/saved URLs, Hourly monitoring, Remote location monitoring, and more!

Go PRO and get the Developer Toolkit today!


Let us know if you run across any bugs or issues and feel free to tell us your thoughts on Twitter (@gtmetrix) or contact us.