The best alternatives to Mockup World are Craftwork Design, Dribbble, and Mocup. If these 3 options don't work for you, we've listed a few more alternatives below.
What do you think of Mockup World?
AssemblyAI— Multilingual Speech-to-Text API with superhuman accuracy
High-quality UX/UI and Wireframe Kits, Illustrations, Templates, and Mockups to make your design workflow faster and easier. Craftwork is a small team of designers and developers. We create our own design stuff and follow new cool products around the internet.
Design quick mocks, directly on your phone.
Napkin is a lightweight user interface design tool made for mocking up quick ideas directly on your iPhone. Core features include: