Basics
An overview of digital accessibility — WCAG, the POUR principles, the legal framework, and what automated testing can (and can’t) do.
What is digital accessibility?
Digital accessibility means designing websites and applications so they can be used by as many people as possible — regardless of visual, auditory, motor, or cognitive limitations. This affects not only people with permanent disabilities, but also temporary limitations (e.g. a broken arm) and situational ones (e.g. bright sunlight on a phone screen).
According to the World Health Organization, roughly one in six people worldwide lives with some form of disability. An accessible website is therefore not a niche concern — it affects a substantial share of all users.
Accessibility also isn't something bolted on afterward; it's most effective when considered from the start — in concept, design, and development alike.
WCAG as a shared standard
The Web Content Accessibility Guidelines (WCAG) are the internationally recognized standard for accessible web content, developed by the World Wide Web Consortium (W3C). They define concrete, testable success criteria — from color contrast to keyboard operability to understandable error messages.
a11y Score checks against WCAG 2.1 at conformance level AA, the standard referenced by most legal requirements (see the EAA & BFSG section below).
The four principles: POUR
WCAG is organized around four overarching principles, often abbreviated as POUR: Perceivable, Operable, Understandable, and Robust.
Perceivable means information must be accessible through more than one sense — for example alt text for images or captions for videos. Operable means all functionality must be usable without a mouse, e.g. via keyboard, and users need enough time to interact.
Understandable means content and behavior must be predictable and clearly worded — including understandable error messages. Robust means content must work reliably with current and future assistive technology, e.g. through valid, semantic HTML.
Legal framework: European Accessibility Act & BFSG
The European Accessibility Act (EAA) is an EU directive that mandates accessibility for certain products and services across Europe. In Germany, it was transposed into national law via the Barrierefreiheitsstärkungsgesetz (BFSG).
Since June 28, 2025, the BFSG applies to many digital offerings aimed at consumers — such as online shops, banking services, e-books, or passenger transport services. Affected businesses generally need to be able to demonstrate WCAG 2.1 AA conformance.
Violations can lead to fines and cease-and-desist claims, depending on the specifics. But the actual purpose matters more than the threat of sanctions: giving more people equal access to digital services.
What automated testing can and can't do
Automated tools like axe-core, which powers this application, can only reliably check a subset of WCAG criteria — estimates put it around 30–50%. They're excellent at catching clear-cut technical problems like missing alt text, insufficient contrast, or invalid ARIA attributes.
What automated testing can't reliably judge: whether alt text is actually meaningful, whether reading order is logical, or whether a complex interaction genuinely works with a screen reader. That requires manual testing and, ideally, feedback from people who use assistive technology day to day.
Automated scans are therefore an important first step, and excellent for catching regressions early in development — but they're not a substitute for a full accessibility audit.
How a11y Score helps
a11y Score loads any URL in a real browser, checks it automatically against WCAG 2.1 AA, and delivers an understandable report within seconds — score, severity levels, and concrete locations in the code.
Accessibility is an ongoing process, not a one-time project — regular scans help catch new problems early, before they go live.