Our Methodology
a11yVault evaluates web accessibility using a three-tier process aligned with WCAG 2.2 A, AA, and AAA criteria.
Three-Tier Evaluation Process
Tier 1: Automated Testing (axe-core)
Every page is scanned using the axe-core accessibility engine, the industry-standard open-source tool maintained by Deque Systems. This detects machine-verifiable issues such as missing alt text, insufficient color contrast, missing form labels, invalid ARIA attributes, and heading structure problems.
Tier 2: Enhanced Analysis
For criteria that cannot be fully evaluated by automated tools, a11yVault performs contextual analysis across 14 enhanced checks. These include evaluating alt text quality (WCAG 1.1.1), images of text (1.4.5), non-text contrast (1.4.11), use of color (1.4.1), and other criteria that require understanding page context and content semantics.
Tier 3: Manual Review Checklist
a11yVault generates a manual review checklist for criteria that require human judgment, such as captions for prerecorded media, timing adjustability, pointer gesture alternatives, and error identification in forms. Human reviewers can record pass/fail verdicts and notes, which are incorporated into the final VPAT report.
Scoring Approach
a11yVault assigns each page a score from 0 to 100 using a severity-weighted penalty model. Violations are classified by impact level: Critical, Serious, Moderate, and Minor. Higher-severity issues carry significantly greater weight in the score calculation. The overall audit score is the weighted average of all page scores.
| Grade | Score Range | VPAT Conformance | Interpretation |
|---|---|---|---|
| A | 95–100 | Supports | Excellent: minimal or no automated violations detected |
| B | 85–94 | Partially Supports | Good: minor issues that should be addressed |
| C | 70–84 | Partially Supports | Fair: notable accessibility barriers present |
| D | 50–69 | Does Not Support | Poor: significant barriers preventing access |
| F | 0–49 | Does Not Support | Failing: critical accessibility failures across the site |
EN 301 549 Mapping
a11yVault maps WCAG 2.2 success criteria to the European accessibility standard EN 301 549 V3.2.1 (2021-03), Section 9 (Web). When exporting VPAT reports, users can optionally include EN 301 549 references alongside WCAG criteria for European compliance documentation.