The best online mockup facilities are provided by Mockup Tool by Fluid UI where you not only create but also share and learn with the fellow creators.
The amazing facilities provided by it are:
- Real time collaboration where you can connect with various other users.
- Live commenting and chat options available so that you can review others’ works and vice versa.
- The designs created on desktop can also be tested on mobile.
- Easily shareable over various platforms.
- Vast number of themes and effects to choose from.