The free version has all the advanced prototyping features. It is cheap, with membership going for $5 a month. A comprehensive collection of fully customizable templates. Supports collaboration.

I like that the most that you can create in a few seconds a wireframe to show graphicly the idea that you are exposing to your team.

NinjaMock is an online tool that allows you to quickly and easily create and design user interface (UI) and user experience (UX) prototypes. It is a popular tool among designers and software developers because it allows them to create interactive mockups and easily share their designs with other team members or clients. With NinjaMock, you can drag and drop predefined elements, such as buttons, input fields, navigation bars, etc., to build your designs. You can also customize these elements and add interactions to simulate how the interface will work in real life. Additionally, the tool has collaboration features that facilitate teamwork, such as the ability to leave comments and receive feedback from other collaborators. The main goal of NinjaMock is to enable designers and development teams to create quick and efficient prototypes without having to invest too much time in programming or developing a complete application. This facilitates the iteration and improvement of the design before starting the actual development process. NinjaMock is available online and offers different subscription plans, from free versions with limited functionalities to paid plans with more advanced features and additional collaboration options.