Because of their small size, icons used in UI’s (user interfaces) should be kept fairly simple.
This is especially true for user interfaces for mobile apps and devices like the iPhone, iPad and mobile devices using the Google Android OS. Since the resolution and screen sizes on these devices are small, monochromatic icons and symbols work very well.
I’ve gathered together 15 simple, single-color icon sets that could be used for UI design.
These icon sets are free for commercial use unless otherwise stated. However, be sure to check the licenses for each set before using on any projects.
The folks at Gentleface have released the free Wireframe icon set–a collection of 244 icons that are free for non-commercial use.
Icons are available in 16×16, 32×32 and 48×48 pixel sizes. The icons come in PNG format.
The Munich icon set is a selection of 60 simple single-color icons that would be great for a user interface.
The set includes icons in 2 sizes 16×16 and 32×32.
Gesturecons is a unique icon set featuring hands performing 35 various multi-touch actions.
This set would be useful for those creating iPhone and Google Android apps. The icons are in vector format, so they could be resized easily and used in tutorials and help guides for multi-touch devices.
Available in vector formats (PDF, EPS, AI).
Iconic is a simple icon set of 114 icons that’s very easy to see even at small sizes.
Icons are available in 14 colors, 5 sizes (8×8, 12×12, 16×16, 24×24 & 32×32 pixels) and in PNG, SVG, SWC and OmiGraffle formats.
Brightmix has released their icon set for free for use on your projects.
The set includes 104 icons in vector (EPS) format.
Token is a very nice set of 128 icons created by brsev.
Icons are available in light and dark versions, as well as 16×16, 32×32, 128×128, 256×256 pixel sizes. Icon formats PNG, ICO (Win).
Token is free for non-commercial use, though an option is available to purchase a royalty-free license for commercial projects.
Axialis has several single-color icon sets in various sizes and colors that would be great for use in mobile app user interfaces.
Great for Android developers, the 30 letter pressed icons that make up the Android Icons set come in PNG format.
They also include the source file (EPS) for customizing.
100+ letter pressed icons available in PSD format.
Tutorial9 has released an nice set of 108 monochromatic icons.
Icons are 32×32 pixel PNG.
Glyphish is a simple set of 130 UI icons that is designed to work for work great for iPhone and iPad apps in toolbars and tab bars.
Set comes in PNG, PSD and AI formats.
Free icon set for iPhone toolbars. Contains 50+ 30×30 pixel PNGs.
Technically, this isn’t an icon set, but rather a font with dingbat symbols. However, this contains many useful audio/video control symbols and icons.
Deziner Folio has released a free 30-icon vector icon set.
The set in available in PSD.
The iPhone UI Icon Set contains 160 PNG icons for use in any iPhone app. Optimized in 2 sizes for the toolbar and tab bar.
This is a high-quality icon set and $69 is not a hefty price if you’re using it for a commercial project.
As always, check the licenses and terms of service for each icon set before using it.