Lightswitch

About

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.