Responsively App is an interesting Open Source desktop application that helps in responsive web development. The ability to display a page for multiple resolutions at the same time allows you to quickly test how the page is displayed on multiple devices. The application is written in Electron. It was based on the Chrome browser, thanks to which we have access to well-known developer tools. There is also an option to take screenshots at hand.
Due to the fact that the tool is relatively young, free and developed by the community, we will certainly run into minor bugs, but in this case it is understandable. Each willing person can contribute to its development. More details can be found directly on the project website.