Neo is a third-party, open source field type for Craft CMS. It builds upon the concept of the Matrix field type with a number of very useful features, most notable of those being that block types use existing fields.
Neo has been built with UX consistency as it's top priority. It aims to look and feel like a part of the core system. The interface has been fine tuned to work smoothly on mobile devices, and in RTL orientation that certain languages require. A lot of work has gone into emulating the feeling of Craft's control panel in the plugin.