Responsive Website Test - Test any website on desktop, mobile, and tablet
Xmind - Xmind is a brainstorming and mind mapping application.
Responsive Viewer - View multiple screen dimensions in one view
MindMeister - Create, share and collaboratively work on mind maps with MindMeister, the leading online mind mapping software. Includes apps for iPhone, iPad and Android.
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.
Coggle - Coggle is a simple, beautiful, powerful way of structuring information.