Responsive Website Test - Test any website on desktop, mobile, and tablet
UI Garage - Specific mobile and web design patterns for your inspiration
Responsive Viewer - View multiple screen dimensions in one view
Muzli - UI/UX and Design Inspiration Chrome Extension
LT Browser by Lambdatest - LT Browser is a free dev friendly browser for developers and testers. You can see mobile view of website on different screen sizes and resolution on 50+ pre installed view ports. You can build, test and debug your website faster then ever.
Design Hunt - Curated design inspiration for everyone