Mockdrop is a free contextual image composition tool that allows users to synthesize their own images and models into a new composite image. It helps you quickly create and share prototypes of applications and provides a simple drag-and-drop interface that allows you to easily create prototypes of applications, including mobile phones, computers, smartwatches, and more. This process does not require any knowledge or technical skills of drawing software. You can simply upload materials and drag and drop images. In addition, Mockdrop's website provides a library resource that includes many common UI elements such as buttons, text boxes, and drop-down menus. You can use these elements to create your application prototypes and save them to your account. You can even share your prototypes with others and get feedback and suggestions from other users.