Are my third parties green?

Check the third party resources used by a website.

All test data is anonymously saved and stored privately. Test results pages are not indexed, but are publicly accessible to anyone with the right URL.

What does this test check for?

Green hosting

Are third party resources being served from a host that is powered by renewable energy, or provides proof to support their green claims?

Data transfer

How much of your site's overall size comes from third party requests?

Effective caching

Are third party resources being cached effectively for repeat visitors/website navigation?

Carbon impact

What is the estimated carbon emissions resulting from third party resources on each page load?

Why does this matter?

The web's carbon footprint

It's estimated that global information and communication technology (ICT) accounts for around 4% of global CO2 emissions. That is about equivalent to Germany's national emissions (the world's 7th largest polluter), and is more polluting than the civil aviation sector.

Third party code is widespread

Over 94% of sites use at least one third-party resource, accounting for over 45% of website requests (2021 Web Almanac: Third Parties). That's a fair chunk of overall website traffic originating from shared, public origins.

Small changes, big impacts.

Serving these widely used scripts from green web hosts, and reducing their transfer size would be a huge step towards a greener web.

Shaving off a single kilobyte in a file that is being loaded on 2 million websites reduces CO2 emissions by an estimated 2950 kg per month.
CO2 emissions on the web by Danny van Kooten

How does it work?

This tool analyses the results on a URL testing with Google Lighthouse. It checks for requested resources that are served from third-party domains, and categorises them based on data from Patrick Hulce's third-party-web repository.

Resources served from subdomains are not considered third-party requests in this test.

Find out the impact of your site's third-party resources.

Test a web page