Presefy is described as 'mobile service for interactive and engaging presentations' and is a Slideshow Maker in the office & productivity category. There are more than 25 alternatives to Presefy, not only websites but also apps for a variety of platforms, including Windows, Mac, Linux and iPhone. The best alternative is LibreOffice - Impress, which is both free and Open Source. Other great sites and apps similar to Presefy are Google Slides, Microsoft Powerpoint, Prezi and Sozi.
Prezi allows anyone who can sketch an idea on a napkin to create and perform stunning non-linear presentations with relations, zooming into details, and adjusting to the time left without the need to skip slides.
We are Ludus, making a slides builder for creatives. We are mixing pro features from Sketch, with the power of internet (Sketchfab, Framer, CodePen ... are some of our integrations). So slides can be truly creative and limitless.