See your site the way your users actually do.
Toggle dark mode, reduced motion, high contrast, and six vision deficiencies — before the page even renders. Real Chrome state, no CSS hacks. Then run a WCAG scan in whatever emulation you want.
Free · no account · runs entirely on your machine
The first-paint problem
Most accessibility tools simulate. Lightswitch emulates.
CSS-injected dark mode lights up your site half a second after the user sees the broken first paint. Lightswitch flips the browser's rendering environment before the page renders — same mechanism Chrome DevTools' Rendering tab uses.
Your site passes contrast checks.
Light theme, default vision, full motion. Everything looks fine on your monitor.
Dark + reduced contrast + deuteranopia.
Click an action icon. The browser repaints in the user's environment.
Suddenly:
- Text disappears into the background.
- Buttons lose affordance.
- Focus states vanish.
What it emulates
Real Chrome state. No CSS injection.
All emulation is delivered via the Chrome DevTools Protocol — the same mechanism the DevTools Rendering panel uses. The page renders exactly as it would for a user with those preferences set.
prefers-color-scheme
Dark / light. Real first-paint, not a CSS class swap.
prefers-reduced-motion
Stop animations and transitions the way the OS-level preference would.
prefers-contrast
More-contrast or less-contrast media-query branches.
forced-colors
Windows High Contrast / forced-colors mode — verify your CSS responds.
Vision deficiencies
Protanopia, deuteranopia, tritanopia, achromatopsia, blurred vision, reduced contrast.
Live contrast overlay
WCAG 1.4.3 contrast audit overlay highlighting low-contrast text in real time.
Per-domain rules
Auto-apply a preset on dev.example.com, never on production. Whitelist or blacklist mode.
Preset rotation
Bundle media features + vision deficiency as a named preset. Click the action icon to rotate.
CSS disable
Strip all CSS for unstyled-HTML accessibility-tree inspection — useful for screen-reader thinking.
WCAG audit — powered by axe-core
Run a scan in any emulated state.
axe-core is bundled and SHA-pinned — nothing fetched at scan time. Score 0–100 with per-violation breakdown, WCAG success criterion, and Deque University deep-link for each finding.
Single-state scan
Scan the page in whatever emulation is currently applied. Quick feedback during a refactor — switch to dark, scan, fix, re-scan.
Multi-state scan
One click runs the same page through default / dark / deuteranopia / reduced-motion / high-contrast and aggregates the findings. Surface issues that only appear in a specific user environment.
Element picker
Scope the scan to a specific DOM subtree. Useful for component-level audits, modals, and design-system review.
Exportable reports
JSON, self-contained HTML, or GitHub-pasteable Markdown. Inspector context (URL, emulation, axe-core version) is embedded so a forwarded report stays reproducible.
Honest disclaimer. Automated WCAG tools identify roughly 57% of issues per Deque's published research. A clean Lightswitch scan does not equal conformance — manual review is still required. The disclaimer is shown everywhere the score appears.
Privacy
Runs entirely on your machine.
axe-core is bundled with the extension and SHA-256-pinned at build time — no remote fetch, no telemetry, no analytics, no remote endpoints. Nothing leaves your browser.
The scan permission is optional. Decline it and the entire emulation feature set still works — only the WCAG audit needs page-content access, and only on the tabs you explicitly scan.
- Manifest V3 — modern, side-panel UI
- Bundled axe-core (MPL 2.0, SHA-256 vendor-integrity check)
- CDP-based emulation — no DOM injection
- Scripting permission requested only on first scan
- No host_permissions in baseline manifest
- 370+ unit tests, Playwright e2e suite
Lightswitch + SiteGuardian
Test locally. Monitor continuously. Audit when you ship.
Lightswitch is the dev-time companion: catch issues before the deploy. SiteGuardian's continuous monitoring catches drift after the deploy. The Site Audit gives you a deliverable for the auditor.
Dev time
Lightswitch
Free Chrome extension. Test before shipping.
Continuous
Pro / Compliance
Weekly accessibility scans on every monitored URL with drift alerts.
On demand
Site Audit
100-page deep crawl with detailed report. €79 (€55 for Pro/Compliance).
Found something? Scan the live URL.
Lightswitch shows you what users see. The free SiteGuardian scan tells you what's wrong site-wide — security, SSL, DNS, email auth, and accessibility.