Screenfly is described as 'Test any website at a multitude of common screen resolutions, including desktop monitors, tablets, and smaller mobile devices' and is an website in the development category. There are 2 alternatives to Screenfly, not only websites but also apps for Self-Hosted. The best Screenfly alternative is Responsa, which is both free and Open Source.
Responsa is an responsive design tool for testing how designs will look across multiple browsers. The open-source tool is freely available online, with the code being accessible for those seeking a self-hosted solution as well.
An interactive viewer to see and test how digital products respond to material design breakpoints across desktop, mobile and tablet.
