Webperf
Webperf Core now supports English language output. Test results, recommendations and feedback are presented in English when you use the -L en flag on the command line.
Many organisations rely on commercial platforms to monitor the quality of their websites. There is now an open and free alternative. Webperf Core is an open source testing suite that analyses everything from performance and security to accessibility, privacy and code quality. The project is maintained by a Swedish community that has been developing the tool since 2018. Over these years, the grades that Webperf Core produces have become a normative reference in Swedish public sector, and expected results are often included as requirements at the outset of new web development projects.
Everything is licensed under the MIT licence. No cost, no vendor lock-in, full visibility into the source code.
What Webperf Core tests
Webperf Core brings together many established testing tools under a single interface. Instead of running separate analyses for different aspects of your website, you get a consolidated overview in one place. The tests cover web performance, accessibility, SEO and best practice through Google Lighthouse, accessibility according to WCAG through Pa11y, security and privacy through Webbkoll, code quality through validation of HTML, CSS and JavaScript, as well as correct adherence to email standards.
All of this builds on other open projects. That is an important part of the philosophy. Webperf Core combines the strengths of several established tools and gives you one place to go for a comprehensive assessment.
Why this matters for your websites
Having test results in your own language makes it easier to communicate findings within an organisation. When a developer can share a report where the recommendations are already formulated in English, it lowers the barrier for non-technical decision-makers to understand what should be improved.
Digital sovereignty is a topic that is receiving increasing attention in Europe. Choosing open source for website quality control is a concrete step towards independence. You need no expensive licence, no cloud-based service with unknown terms. Everything runs locally or in an environment that you control yourself.
It is also about following established standards. The tests in Webperf Core largely measure compliance with W3C standards, WCAG guidelines and best practice for security and privacy. These are not arbitrary opinions about quality, but assessments grounded in internationally recognised norms.
Getting started
Webperf Core is a technical tool aimed primarily at developers or the technically curious. You will need Python 3.13 or later, Node.js and a browser such as Chrome or Firefox installed on your machine.
The approach is to download the source code from GitHub, install the dependencies and then run the tests from the command line. Let us say you want to test how well The Guardian protects its visitors' privacy. You would type the following in your terminal:
python default.py -t 20 -u https://www.theguardian.com -r -L enHere -t 20 means you are running the privacy test, -u specifies the web address you want to test, -r gives you a readable report, and -L en ensures that the output is in English.
If you would rather run a broader test of the GOV.UK website with Lighthouse, covering speed, accessibility, SEO and best practice, you can try:
python default.py -t 30 -u https://www.gov.uk -r -L enOr perhaps you want to test accessibility specifically with Pa11y:
python default.py -t 18 -u https://www.gov.uk -r -L enThe result gives you a weighted grade and concrete suggestions for improvement.
For the easiest way to get started, you can also run Webperf Core through Docker, where all dependencies are already set up. And for those who prefer a fully automated approach, there is a ready-made setup for GitHub Actions.
Try it yourself
Webperf Core is built on the idea that the web gets better when we share knowledge and tools openly. The Swedish community has shown that a small, committed group can create something that has real impact on the quality of public and private websites.
Now that the tool is available in English, I hope that more people across Europe and beyond will try it and perhaps also contribute. That could be anything from improving translations to reporting bugs or suggesting new features. The community is available on Slack for those who need help getting started.
Good websites are built with good habits. Regularly testing and improving quality is one of the most important habits we can have as web professionals. Download Webperf Core from GitHub at github.com/Webperf-se/webperf_core and run your first test today.