Whimsical Wireframes - Lightning fast wireframing with real-time collaboration.
Appcues for Product Adoption - Make your product easier to use. Code-free.
Balsamiq Cloud - Fast, approachable, collaborative wireframing
Usetiful - Fight user churn with great user onboarding. Interactive product tours and smart tips significantly improve your user retention.
Justinmind - Define awesome experiences through wireframes & prototypes.
UserGuiding - User onboarding made easy, for less. Create product walkthroughs in a couple of clicks, without breaking the bank.