Lightswitch

Free Chrome extension for accessibility + media-state testing. Run a WCAG scan on any page. Emulate dark/light mode, reduced motion, high contrast, vision deficiencies — see your site through your users' lenses, no CSS injection. WCAG AUDIT (POWERED BY AXE-CORE) Run a scan on any page and get a score 0–100, per-violation report with the relevant WCAG success criterion and a Deque University deep-link. • Default scan is fast and single-state — runs in whatever emulation you currently have applied. Opt in to multi-state to compare findings across default / dark / deuteranopia / reduced-motion / high-contrast. • Element picker — click a component, scan only that subtree. • Export as JSON, self-contained HTML (opens in a new tab), or GitHub-ready Markdown. • Inspector context (tab, preset, filter, debugger state) is bundled in every export so a forwarded report stays reproducible. • Honest framing: automated WCAG tools identify ~57% of issues per Deque's research. A clean scan does not equal conformance — the disclaimer is shown everywhere the score appears. EMULATION (THE CORE FEATURE) • prefers-color-scheme (dark / light) • prefers-reduced-motion • prefers-contrast (more / less) • forced-colors • Vision deficiencies — protanopia, deuteranopia, tritanopia, achromatopsia, blurred vision, reduced contrast Delivered via the Chrome DevTools Protocol. No CSS injection, no overlays, no late-rendering surprises — the page sees the emulated state from first paint. PRESETS, ROTATION, DOMAIN RULES • Bundle media features + vision deficiency as a named preset. • Click the action icon to rotate through presets you've marked for rotation. • Per-domain auto-apply rules with whitelist / blacklist filter mode. • Optional custom CSS injection per preset (off by default). • CSS disable for unstyled-HTML accessibility-tree inspection. • Live contrast-audit overlay highlighting low-contrast text per WCAG 1.4.3. EXTRAS • Side-panel inspector — current tab, applied preset, filter state, debugger attach status. • JSON export / import for preset backups. • Context-menu preset picker. • Action-icon glyph follows the applied preset (or your OS theme when no preset is active). PRIVACY + PERMISSIONS Lightswitch runs entirely on your machine. axe-core is bundled — nothing is fetched at scan time. No telemetry, no remote endpoints, no data leaves your device. • debugger — required for the DevTools Protocol emulation, the core mechanism. • tabs, storage, contextMenus, sidePanel — UI surfaces. • scripting + host access (<all_urls>) — optional, only requested when you first run a WCAG scan. Used to inject axe-core into the active tab. Decline and emulation features still work. ATTRIBUTION axe-core © Deque Systems, Inc., licensed under MPL 2.0. A free tool from siteguardian.io.