This StumbleUpon icon is made in Material Design style developed by Google. This style is based on extremely simplified shapes, thin two-pixel lines, and is optimized for 24x24 px. Unlike other vector icon packs that have merely hundreds of icons, this icon pack contains 5,500 icons, all in the same style and quality.
Idea of StumbleUpon Icon by Anonymous
We've received the idea on July 18, 2012 and created the icons on July 22, 2012
I know some have been already posted, but this unifies all of them plus more. 1. Soundcloud 2. Pinterest 3. Stumbleupon 4. Wikipedia 5. Instapaper 6. Tumblr 7. Dribbble