Outline style icons are very useful and truly popular nowadays. They easily complement any subtle and elegant design, making it look more sophisticated and harmonious. Of course, they won’t provide great contrast since they rather thin to easily stand out on a background alone, so before implementing them on your project you should definitely take into account what type of a canvas you will have. Also such type of icons are more appropriate for app interfaces, rather then for web design that richer in elements, decorations and simply greater. Outline style icons shoudn’t be lost.
Today I have decided to bring together comprehgensive collection that consists of polished and minimal outline icons that serve various purposes. You can use icons free of charge, but take a look at its license, since some of them have restrictions.
3.Day in the Life Icon Set by Ainsley Wagoner 
5.iOS 7 Tab Bar Icons by Pixeden 
6.35 Thin Icons Set by Dmitri Litvinov 
8.Jollyicons – set of amazing handdrawn icons 
10.CloudIcons Now Available For Free Download by Axel Herrmann 
11.50 Simple and Neat Vector Icons 
12.80 Mini Icons (PSD + Icon Font) 
13.Simple Icon Set by Joshua Andrew Davies 
14.Jericon Mini 16px V1 by Jer 
15.Circle Icons by Tomas Korosi 
18.FatIcons 
19.Thin Flat Icons Freebie by Ignacio Valdés Reyes 
21.Weather Icons Part I by Pieter Goris 
22.20 Glyph Icons by Martin J.Berthelsen 
23.Sketch icon set by Pausrr by Pausrr 
24.Washing Icons – Free icon set by Dominik Rezek 
25.Weather Icon PSD by Onlyoly 
26.Minimal Outline Icons Freebie by Martin Maričák 
28.Sunday Market by Ezhi Stolz 
29.24 Free Icons by Michael Dolejš 
31.Other icons 
32.Nooby Icons by Eduardo Higareda 
33.Sharing is Caring by Axel Herrmann 
34.44 Shades of Free Icons by Victor Erixon 
35.Weatheroo 
36.Steadysets 
38.Freebie: UX Icons by Nicki Stearns 
39.36 Circle Icons by Michael Reimer 
40.Climacons by Adam Whitcroft 
41.Linecons 
42. Simple Icon PSD by Onlyoly 
44. Outline Icon Set by Jake Culp 
46. iOS7 UI Kit 
