UX tools range from rudimentary (pen and paper) to highly sophisticated (web applications and tech tools). Here is a brief roundup of popular options.
Balsamiq (https://balsamiq.com) bills itself as a ‘rapid wireframing tool’ and is great for creating fun, low-fidelity wireframes and simple prototypes.
Axure (www.axure.com) is an all-purpose prototyping tool that allows you to create fully interactive wireframed websites without needing to code anything. A useful feature is that it also generates technical specifications for developers to work from based on the interactions and links created in the prototyping process.
Gliffy (www.gliffy.com) is a web-based tool that allows you to create a wide range of diagrams, everything from wireframes to sitemaps to charts.
Invision (www.invisionapp.com) is a web based tool that allows you design prototypes across web and mobile.
Morae (www.techsmith.com/morae.html) is a good place to start if you’re looking for a web-based replacement for user labs.
Pop (https://marvelapp.com/pop/) or Prototyping on Paper, is a free app for prototyping apps on mobile.