Revive Adserver - The free open source ad server formerly known as OpenX Source

SimilarWeb - SimilarWeb.com is a website analysis tool that gives you analytics information for any website.

Google Ad Manager - Grow revenue wherever your users are with an integrated ad management platform that surfaces insights for smarter business decisions.

Site Rank Data - View historical rank information of websites via time series charts.

Kevel - Kevel's APIs make it easy for engineers and PMs to quickly launch a fully-customized, white-labeled, server-side ad server.

Quantcast - Quantcast Corporation is a digital marketing company that provides free audience demographics measurement and delivers real-time advertising.