About WSG Check
An open-source tool for evaluating websites against the W3C Web Sustainability Guidelines (WSG) .
Purpose & Methodology
WSG Check analyses a web page's HTML and HTTP responses against 80+ automated and semi-automated checks derived from the W3C Web Sustainability Guidelines. Each check maps to a specific guideline and provides a pass, fail, warn, or info result along with an actionable recommendation.
Because WSG Check uses static analysis only (no headless browser), some checks that require JavaScript execution or network timing — such as Core Web Vitals — are out of scope. Those are flagged in every report with links to complementary tools like Google PageSpeed Insights .
Why I Built WSG Check
The W3C Web Sustainability Guidelines are thorough, but they read like a standard, not a to-do list. Most teams I talk to agree that a lighter web is a better web, then stall on the question of where to start. Carbon calculators hand out a score without a fix, and performance tools measure speed without saying which guideline a problem maps to.
I wanted the sustainability equivalent of an accessibility linter: something that runs in seconds, points at specific success criteria, and tells you what to change. WSG Check is that tool. It is open source so that anyone can see exactly how a score is calculated, and it runs as a website, a CLI, and a CI step so the checks can live where the work happens.
Want Help Acting on Your Report?
A report tells you what to fix. Doing the fixing, while keeping design, content, and business goals intact, is the harder part. Through Sustainable Websites, I help teams turn WSG Check findings into a prioritised plan and then into lighter, faster, lower-carbon sites.
If your score was lower than you hoped, or you need to show progress against the W3C guidelines, let’s talk.
Visit SustainableWebsites.com ↗How Scoring Works
Each check contributes a score of 0–100, weighted by impact (high, medium, low). The overall sustainability score is a weighted average across all scored checks. Checks with status info or not-applicable are excluded from the average.
Grade A
Score 90–100
Grade B
Score 75–89
Grade C
Score 60–74
Grade D
Score 45–59
Grade F
Score 0–44
Sustainability Statement
WSG Check is itself designed to minimise environmental impact:
- Static analysis only — no headless browser, no Chromium binary
- Zero third-party JavaScript on the frontend (Park UI + PandaCSS generate static CSS)
- Server-side rendering for fast initial load with minimal client-side hydration
- In-memory result store with automatic TTL eviction (no database)
- Follows W3C Web Sustainability Guidelines in its own implementation
Who I Am
I’m Ivan Storck, a software architect in Seattle. By day I am a Senior Solutions Architect at lululemon, working on content management, design systems, and brand technology. Before that I co-founded Code Fellows, taught Ruby and JavaScript to several hundred bootcamp students, and spent six years on the teaching faculty of the University of Washington’s Rails certificate program.
Outside of that I take a small number of fractional CTO engagements and build sustainability tooling for the web. More of my work is at ivanstorck.com.