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LT Browser vs Responsive Design Checker: catalog facts
LT Browser	Responsive Design Checker
Freemium Free to download, with paid tiers as part of the TestMu AI platform.	Free Free to use.
Windows, macOS, Linux	Web
Views several device viewports side by side More than 50 device screen presets	Previews several screen sizes from one page Nothing to install
Device views are emulated rather than real hardware Tied to a commercial testing platform with paid tiers	Limited to five requests every five minutes Simulated viewports, not real devices
Downloadable app	Web application
Closed source	Closed source
License not stated	License not stated
Not stated if an account is needed	Not stated if an account is needed
Not stated if it works offline	Needs internet
Official website Full listing and sources Checked September 23, 2026	Official website Full listing and sources Checked September 23, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.