Responsive testing for developers, designers & QA
Find responsive bugs. Capture the evidence. Hand off a fixable report.
Test one URL across modern mobile, foldable, tablet and desktop layouts. Capture screenshots, record reproducible QA flows, and connect frontend issues to the exact viewport and evidence.
Free Forever · No account required for core testing · No ads · Pro trial available after your first successful test
Current Store release: v2.0.0. v2.0.1 is the next reviewed update and will become available only after Chrome Web Store approval. The version currently available for installation is shown on the Store listing.
One workflow
URL → responsive preview → evidence → reproducible QA flow → Results
Start with Standard Coverage instead of configuring dozens of controls. When you need depth, open current devices, foldable states, Breakpoint Sweep, screenshots, Interactive Test, QA Flow recording and detailed Results.
Responsive testing
Mobile, foldable, tablet & desktop
Compare representative screen risks side by side, use current device families, rotate views, synchronize scroll and test seven common CSS breakpoint widths.
Screenshots
Evidence, not just previews
Capture device views and multi-device comparisons. Redact sensitive visual content locally before saving or copying. Pro adds full-page and professional batch evidence workflows.
QA Flow
Reproduce what happened
Record clicks, navigation and safe input metadata into ordered QA steps. Passwords, payment fields and typed values are not stored by the recorder.
Foldables
Outer and inner states matter
Test book-style and clamshell layouts as explicit cover/main or outer/inner states. Device descriptors keep source and verification status instead of pretending physical pixels are browser CSS viewports.
Results
Know what to fix and retest
See deterministic responsive, accessibility, UX and runtime evidence by affected viewport. Pro adds deeper cause, implementation guidance, professional exports and retest handoff.
Local-first
Keep routine QA on your machine
Core previews, captures, flow evidence, redaction and saved Free work stay local. Mobile Lab does not require cloud screenshot storage or session replay.
Free Forever + Pro when work gets deeper
Use Mobile Lab regularly before you ever need to pay.
- Unlimited core responsive test sessions
- Standard Coverage + Mobile/Foldables/Tablet/Desktop + 7-width Breakpoint Sweep
- Multi-pane responsive testing with no plan-based pane cap; large device sets add progressively to protect workspace performance
- Basic screenshots with local redaction
- Core Results with real issue evidence
- 3 saved test setups
- 3 saved QA flows, up to 20 steps each
- No account required for core use
- Full verified device catalog and current foldable states
- Professional evidence, deeper diagnosis and repeated QA workflow depth
- Unlimited saved test setups and QA flows
- Full-page and advanced batch evidence
- Rich annotation and professional exports
- Deeper Results, cause/fix/retest guidance and agent-ready handoff
- Up to 2 active personal browser installations
14-day Pro trial becomes available after your first successful test. No card is required and there is no automatic charge when the trial ends.
Install Free, then try ProExisting paid subscribers keep their current subscription price unless a separate migration is explicitly agreed. New v2 subscriptions use the prices above. First paid charges have a 7-day money-back window subject to the published refund policy and applicable law.
Accuracy boundary
Emulation is fast QA—not a claim of physical-device certification.
Mobile Lab uses Chromium-based responsive preview and browser emulation. Named device presets record source/verification status, and new foldable CSS metrics are not labeled authoritative until browser/runtime evidence supports them. Final critical journeys should still be checked on the target real browser/device when required.
Privacy
Telemetry is separate and optional
After a successful test, you may opt in to first-party aggregate product events. We do not send URLs, hostnames, DOM/page content, screenshots, form values, credentials, search history or session recordings as product analytics.
Permissions
Access exists for the QA job
Broad page access, tabs, downloads, debugger and declarativeNetRequest support arbitrary-site responsive preview, blocked-site recovery, browser emulation, captures and QA evidence. The Store disclosure explains why each permission is needed.
Support
Billing, activation or product issue?
Email ml.support@marsci.cc. Do not send card numbers, passwords or other secrets.