The application was developed by Steffen Gerlach and you can check out its quality on the official A Sharper Scaling website.
Here, the author compares the enlarged image with A Sharper Scaling with two other popular applications, Bicubic Interpolation (BI), the Preserve Details tool in Photoshop.
According to the PetaPixel review, A Sharper Scaling produces better images than the other two. In addition, this application is rated as compact, simple interface and very easy to use.
At this point, A Sharper Scaling is still a free application and only available for Windows (from Windows 7 to Windows 10).
You can download it here: