High quality png icons are sometimes hard to find. There are some of the websites where you can download the icons for free and use them for commercial and personal websites. Please read the license before using the icons. Although they are free but for some of them you need to buy a license for very less price.

1. artdesigner.lv

Free PNG high quality icon set

2. dryicons.com

download png icons for free

3. Round PNG windows icons

Round png blue icons for windows system

4. Free e-commerce icon set for website

creditcard icons high quality

5. webappers.com

Big list of png small and big icons, high quality social media icons download them for free
small social media icons

6. 3D social media icons for free

3D social media png icons high quality

7. yootheme.com

They have hell lots of big high quality png icons for credit cards, social bookmark, halloween etc and best thing is all are free to download.

big credit card png icons for free

big high quality social bookmarking png images

download free high quality halloween png icons