Ads.txt stands for Authorized Digital Sellers and is a simple, flexible and secure method that publishers and distributors can use to publicly declare the companies they authorize to sell their digital inventory.
ScorecardResearch is service of Full Circle Studies, Inc., is part of the comScore, Inc. market research community, a leading global market research effort that studies and reports on Internet trends and behavior. Here are all the website that put a pixel of Scorecard Research
StatCounter, a free online visitor stats tool. It offers its members the chance to grow and improve their online businesses by allowing them to monitor the number of hits to their website; the geographical location of visitors; the various pages a visitor views; keywords used to find the site plus other features.
Google+ platform websites integration using the Google+ platform tag.
Let visitors recommend your content on Google Search and share it on Google+.