What are some alternatives?
When comparing Responsa and Polypane, you can also consider the following products
BrowserPage - The most intuitive Responsive Design Checker online tool for your Website.
Blisk Browser - A Chromium-based browser for Web developers
Blisk - Download Blisk - a browser for web developers. Blisk is a toolbox for development, debugging and testing: emulation, sync, analytics, and screenshots.
LT Browser by Lambdatest - LT Browser allows you to perform live mobile view debugging of your website on different devices. You can test on mobile and tablet simultaneously on our browser and debug user issues and see their impact on the go on a wise range of mobile devices.