Web GUI Kit. Designed with users in mind, Web GUI Kit comes as layered vector shapes, which means you can resize them any time without any quality loss! (Image Source: Hongkiat)
Rainbow. Rainbow UI kit contains every fundamental elements including login interface and file uploading interface for your web design need. And like a rainbow, it’s beautiful. (Image Source: Hongkiat)
Awesomeness Widgets. 480,000 pixels of awesomeness compressed into one PSD file, and it’s free for you. (Image Source: Luis M Ruiz)
Balio. Balio UI kit will prove handy to you, as it is a practical, useful collection of web design elements containing buttons, stickers, icons, pagination, menus, login form and more for your personal and even commercial use! (Image Source: Webdesigner Depot)
Beige. Delivered with a slight retro feel, Beige is ready to make your website clean and slick. (Image Source: MediaLoot)
Pillow. Calm colors and a comfortable design, that’s the Pillow UI set. (Image Source: Dribbble)
Blue Milk. Looking for a fresh design that pops, and comes in 100% vector for infinite scalability? Blue Milk will fulfill your taste. (Image Source: Ryan Warner)
Clean UI Pro. How about some UI elements that cleanse out the messiness of your website? They are also delivered as well-organized layers for your quick deployment. (Image Source: Purity Pixels)
Square. Embrace the flat web design trend with Square, a mega set of sleek elements and interfaces to create your website, web application or even iPhone app. And yes, you don’t have to pay a cent for this. (Image Source: Designmodo)
Polaris. Are you ready for flat web design? If that’s the case, this set of extremely polished flat elements is ready for your use in any second. (Image Source: Designmodo)
Impressionist. Though it comes as a part of the premium version, Impressionist UI kit is still one of the most impressive kits you can get for your website. (Image Source: Designmodo)
Futurico. It is hard to get leads if you don’t have a futuristic, more importantly professional user interface. Futurico could help tackle this issue easily. (Image Source: Designmodo)
White Blue Web. White and blue are always the best combination for a visitor-friendly site! (Image Source: PSDchest)
Prime. A premium user interface designed for free giveaway. Prime is also carefully developed to help you update the color easier, talking about user-friendliness! (Image Source: MediaLoot)
Mega UI Pack. A mega UI pack with ultra smashy design, could you ask for more? (Image Source: Kim)
Sticky Butterscotch. Besides the sweet name, Sticky Butterscotch’s detail is awesome enough to attract 1000+ likes from Dribbble professionals. (Image Source: Made By Thomas)
Got Wood. What you see is not what you get, as Got Wood actually debuted with over 100 hand-crafted design elements for whatever use you prefer. (Image Source: MediaLoot)
Phoebus. You don’t have to worry about design resources for your site with this Phoebus set, also a red version named Ares is freely available to you too. (Image Source: DesignShock)
Apollo. Get a bit more stylish with Apollo, quality guaranteed! (Image Source: DesignShock)
Hades. Hades could be your best bet if you’re building a wild, unique service on the web. Just look at its glossiness! (Image Source: DesignShock)
Kick Out. Jan Semler is generous enough to give away his kick-ass GUI set pre-designed with 4 color options. Also in case you don’t know, it’s simple to change the color to your liking! (Image Source: Jan Semler)
Light Web. I personally love the typography, and totally believe that Light Web can be used to transform any website with elegant results. (Image Source: Mihai Peticã)
LinkedIn iPad Redesign. You don’t need too many icons to be content, LinkedIn iPad Redesign can tell you why. Additionally this layout suits well for personal portfolios too. (Image Source: Zeki Ghulam)
Dashboard. Perfect UI layout for kickstarting web application, and it will even ease your editing pain with its resizable shape layers! (Image Source: GraphicsFuel)
Smooth Web App. Though web applications have existed years ago, it’s surprisingly hard to find UI kits for it. Fortunately MediaLoot has prepared one for you! (Image Source: MediaLoot)
Black Dashboard Interface. A mindfully crafted design, loaded with a simple graph, progress meter, table design, and navigation menu for your inspiring web app. (Image Source: PixelsDaily)
Black UI. “It’s a bit unusual, because it’s almost completely black, but it was one of my long time obsessions to craft a complete slick black on black UI.” (Image Source: Alex Patrascu)
Media Black. Media Black is a combination of neat web, media and application elements for all-purpose use, just apply them with your creativity! (Image Source: Webdesigner Depot)
Sleek Web. If you are forging a technology-oriented site, these dark elements encrusted with blue neon glow could persuade your reader’s eyes into more site discovery. (Image Source: CreativeFan)
Ruthenium. It’s hectic to try new yet unconventional color schemes with your site design, but now you have the chance to get one of them instantly right with the Ruthenium kit. (Image Source: despoth)
Sign In Form. This little gem will elevate your sign in form into an entirely new level of aesthetics. (Image Source: Mahdi Pourebadi)
Solid. Any word will look amusing if it’s smashed onto these squishy elements. On top of that, don’t you just want to keep pressing them? (Image Source: Design Kindle)
Sleek UI Elements. The only bad thing about this pack is it does not come as a complete kit, since the design is not only elegant, but practical. (Image Source: Design Kindle)
Super Clean. Simplicity, cleanliness and better user experience is what you can get with Super Clean. (Image Source: WeCreate)
UI Kit. As long as you start with this kit, you won’t go too far from minimalism and professionalism. (Image Source: Hüseyin Yilmaz)
Metrostyle. Metro UI is the new cool, and this Metrostyle UI kit will prove to you this fact with its meticulous elements, and 3 additional color options! (Image Source: Josep Roselló)
Web UI Set. Don’t let the preview image fool you, as this package is actually released with 70+ interface elements, ranging from icons to buttons to menus, to cater to your every need for website creation. (Image Source: DuckFiles)
Web App UI. Web apps with flat design is rapidly becoming a trend in the web, so why not be part of the pioneering group? (Image Source: Blaz Robar)
YouTube. As the web is heading toward the future of sharing short videos rather than text, this template is your all-in-one solution for creating video web app. (Image Source: Jackie Tran)
Google+ UI Kit. Are you a big fan of Google+, particularly its flat design? Then this kit could be a huge help for you to create another web giant like G+. (Image Source: Alexey)
Mobile GUI Set
The web is more driven towards mobile nowadays, but designers have adapted to the trend well enough to generously offer these free premium GUI kits to developers. Take these and you are few steps closer to success!
Flat. With Flat, your users are guided to focus intensively on content. (Image Source: Riki Tanone)
Flat 2. A variation from Flat (mentioned above) this pack is more focused towards blogging. (Image Source: Riki Tanone)
Flat UI Pack. Another Flat UI pack that offers more variety, so combine them all and you’re good to build a full-fledged mobile app! (Image Source: Andy Law)
Mobile UI Kit. Want a kit with Metro variation and flawless elegance? Here’s the one for your app. (Image Source: Abhimanyu Rana)
Insta GUI. Yes, an Instagram GUI for your insta app design. The level of detail made me think that it’s from official Instagram team! (Image Source: Adrien Olczak)
Dark Chest. Combine this with Part 2 and Part 3, and you now have one of the most visually appealing designs for mobile app. (Image Source: PSDchest)
Caramel UI. Been criticized about app design’s being too flat? You know what to do next. (Image Source: Rockable Themes)
Lookamore. Android is dominating the world, and you don’t want to waste much time on app design to ride on this bandwagon. Lookamore is the quick yet promising fix and best of all, you can use it without any attribution. (Image Source: Artem Tolstykh)
Mobile App Kit. If you are into mobile purchase businesses, this is a 21MB, 4-page complete layout for iOS application. I can’t see a reason of not giving it a try. (Image Source: Tempees)
Primera. Primera embraces slightly darker designs than most apps, but don’t worry, it’s also bundled with neutral light and orange brown versions to get your app lit up! (Image Source: Luis M Ruiz)
Pandora. “This is a great collection of base and custom elements that will be helpful for iOS designers and developers to bring their work to reality and design something beautiful for their apps.” (Image Source: Designmodo)
Heads Up Display. Surprise your competitor with this pack, and now you have no more excuse not to build an app with exceptional design. (Image Source: MediaLoot)
Simple Bold. Windows Phone 8 is surely rising with its Windows 8 sibling, so get yourself prepared with this brilliant kit. (Image Source: Gentian Edwards)
Transparent UI Kit. Definitely one of the kits with precise design that you don’t want your competitors get before you do. (Image Source: Design Kindle)
Retina iPhone App. Although most freebies implement vector shapes that can resize infinitely, this set will save you even more time and effort by provide you a retina-ready version. (Image Source: Kb’s portfolio)
Total Retina. An ideal design kit for any amateur app developer, you can’t go too wrong with these standard, yet complete designs. (Image Source: Josep Roselló)
iPad App. Planning to develop a social iPad app? Then here’s a huge UI layout for you aspiring dreamers. (Image Source: Kb’s portfolio)
Mail App. Whether you want to make an iPad or iPhone mail-related app, you can just take the elements out from this layout to fulfill your creativity. (Image Source: Aaron Sananes)
Web and App. Intended to be a mix between web and mobile app, this set could fit any kind of project mindlessly with its simplistic approach. (Image Source: vasiligfx)
Beautiful Kit. Just as its name suggests, this is a fancy kit with luminous colors to brighten up your user’s mood. (Image Source: Jamie Syke)