Daylight by Sonde
Illuminating accessibility for software
According to the WHO, one in six humans worldwide (including 1 in 4 Americans) lives with a disability that affects how they experience the web — from low vision and color blindness to motor impairments, cognitive differences, and age-related challenges. The Web Content Accessibility Guidelines (WCAG) exist to address this global need. When software fails these guidelines, it fails over a billion people.
Software should support infinite diversity in infinite combinations. Daylight scans real websites, measures accessibility conformance, and openly publishes the findings because accessibility matters.
Every Finding Has a Source
Sonde findings are traceable. Every finding records:
- The specific WCAG success criterion violated
- The probe that detected it (and its version)
- The DOM element or page context where the issue occurs
- A remediation suggestion
No black boxes. No unexplained scores. Every number in a Daylight report can be traced to its source.
From Findings to Fixes
Daylight reports don't just identify problems — they suggest solutions. Each finding includes remediation guidance: what to change, why it matters, and how to verify the fix.
Nominate a Site
Know a public website that should be on a leaderboard? Nominate it via our GitHub Discussions. We review nominations and add qualifying sites.
About Sonde
Sonde is a holistic software system analyzer. It understands coding languages, build configurations, dependency graphs, compliance posture, and runtime resources, then runs probes that annotate findings.
The Sonde Score
Every site receives a Sonde Score from 0 to 1000, computed from automated accessibility analysis across multiple dimensions:
- WCAG 2.1 Level A and Level AA criterion coverage
- Finding severity and density (critical findings weigh more)
- Cross-page consistency (one clean page doesn't offset five broken ones)
- Probe detection confidence (each finding traces to a specific rule)
Sonde currently evaluates 45 WCAG success criteria using Sonde live probes (keyboard navigation, color contrast, reflow, media accessibility), accessibility tree analysis, and axe-core DOM rules.
Try Our Themes
Sonde created WCAG 2.1 AA-verified CSS themes built on a shared semantic token layer. Daylight is one of them — the others power our audit reports, dashboards, presentation decks, and a high-contrast AAA baseline for low-vision users.
How we derive compliance labels
Every Daylight VPAT and audit report tags its NIST 800-53 / FedRAMP coverage with the upstream OSCAL release the data was derived from, never a hand-curated mapping. Crosswalked controls excluded by the active baseline selector are surfaced explicitly as (not in baseline) rather than silently dropped.
- NIST 800-53B baselines and the NIST PRIVACY overlay come from usnistgov/oscal-content (release pinned in
catalogs/controls/nist-800-53/). - FedRAMP Rev 5 LOW / MODERATE / HIGH baselines come from OSCAL-Foundation/fedramp-resources (commit pinned in
catalogs/controls/fedramp/). - The selector + transparency contract is documented in the open FedRAMP vs NIST baseline modeling plan.
Each rendered VPAT and audit HTML carries machine-readable provenance via <meta name="sonde-oscal-catalog"> (always) and <meta name="sonde-baseline"> / <meta name="sonde-overlays"> (when a selector is active), so third-party scrapers and archivists can identify the methodology a published artifact was generated under.
Disclaimer: This report presents the results of automated accessibility analysis and is provided free of charge, as-is, without warranty of any kind. Findings are generated by software, not by human accessibility experts, and may contain errors or omissions. Automated testing can detect approximately 30–40% of accessibility issues; manual expert evaluation is recommended for complete conformance assessment. Scores reflect algorithmic analysis under a published methodology open to public review — they are not legal determinations of compliance. Results reflect the state of the website at the time of scanning and may change as the site is updated. Nothing in this report constitutes legal advice. Sonde assumes no liability for decisions made based on these results.