Coming to Mockups or Prototypes or Wireframes, every User Interface designer or web designer or any designer you take will do a visual representation of their thoughts in different ways from laying out their ideas on either in a blank paper or Photoshop or graph paper or any other tools or software’s which they are comfortable with.

And it’s a good practice to start with low fidelity prototypes or wireframes or mockups as it will be easy and quick to update the mockups as per the changes suggested in a group discussion or with clients.
I always start with wireframes; I hope every designer, from fashion to mechanical designers, begins with a low-fidelity prototype. It’s been a long time since I looked at the latest wireframing software or tools available in the market, so I just had a glance, and here are the few that I found to be very handy, practical, accessible, and premium tools.
MockFlow
Super-easy Wireframing Design, collaborate user interface concepts for your software and websites.
Moqups
Moqups is a nifty HTML5 App used to create wireframes, mockups, or UI concepts, prototypes depending on how you like to call them.
WireframeSketcher
WireframeSketcher is a wireframing tool that helps product managers, designers, and developers quickly create wireframes, mockups, and prototypes for desktop, web, and mobile applications. It’s a desktop app and a plug-in for any Eclipse IDE.
UXPin
UX DESIGN TOOLS BUILT BY UX DESIGNERS: UXPin’s Collaborative Approach Cuts Cost & Confusion, Making Work Fun!
InvisionApp
Transform Your Designs Into Beautiful, Interactive Web & Mobile Mockups!
JustInMind
The best platform to define web and mobile apps with rich interactive wireframes
Balsamiq
Balsamiq Mockups: Rapid Wireframing Tool, over 80,000 companies create their software with the help of Balsamiq Mockups.
Interface 2 for iPhone & iPad
Use Interface 2 to create pixel-perfect mockup screens using native iOS widgets, right on the iPhone or iPad.
JustProto
Wireframing With JustProto Saves You AND Your Clients Time, Money & Headaches!
iMockups for iPad
iMockups for iPad is the premiere mobile wireframing and mockup app for your web, iPhone, and iPad projects.
Proto.io
Silly-fast mobile prototyping – Create fully-interactive high-fidelity prototypes in minutes that look and work exactly as your app should.
Mockingbird
A mockingbird is an online tool that makes it easy for you to create, link together, preview, and share your website or application mockups.
Mockup Builder
MockupBuilder is a new look to solve old problems with prototyping and sharing sketches with customers.
HotGloo
HotGloo will change the way you create and experience wireframes.
Pencil Project
An open-source GUI prototyping tool that’s available for ALL platforms. The pencil is built to provide a free and open-source GUI prototyping tool that people can easily install and use to create mockups on popular desktop platforms.
FlairBuilder
The Better Way to Wireframe Websites and Mobile Apps. FlairBuilder is a prototyping tool that lets you create interactive wireframes for websites and mobile applications. It’s easy to learn and use and comes with lots of options.
Axure
Design Interactive HTML Prototypes for Web & Apps with Axure RP.
If you ask me which is my favorite among these for quick mockup preparation and sharing the same online – then I would consider Moqups :)
Friends, any good tool I am missing here? If so, please share, it would be helpful for me, and I will even update this article with that prototyping tool. I will keep editing this post going forward with new tools. And hope you found these Mockups or Prototypes or Wireframes Tools or Software lists to be very useful.