Download Free Icons No Attribution Images. These two free image sources also happen to be cc0 license (creative commons no rights required licensing), which means attribution isn't even required. 40+ vectors, stock photos & psd files.
With handy icon packs you can easily stay on attribution requirements range, so be sure to check it before downloading.
There are free sets around but it might be a very nice gesture to consider choosing those that do require you to recognise them. 2739 icons can be used freely in both personal and commercial projects with no attribution required, but always appreciated and 1476 icons require a link to be used. Insert the attribution on the page of the icon (for example in the page footer) or on the imprint page. Most icons there are free for use under the cc license (which means attribution is required).