SimilarWeb - SimilarWeb.com is a website analysis tool that gives you analytics information for any website.
StackAdapt - Native advertising demand side platform.
Site Rank Data - View historical rank information of websites via time series charts.
MGID - MGID is a native advertising platform to acquire visitors, monetize websites, build new audiences, and grow traffic.
Website Informer - Website.informer: complete data lookup & free aggregated report on any domain including whois, visitors, IP & DNS details, competitors, owners, etc
Google Ad Manager - Grow revenue wherever your users are with an integrated ad management platform that surfaces insights for smarter business decisions.