On April 18th, 2012, Google announced to the industry that it would be rolling out its own implementation of the 3MS viewability standard for online display ads, namely Active View. Google’s stated aim is both to make display marketing more appealing to brand advertisers and also to reduce uncertainty for direct-response marketers.
Today, spider.io, a European ad technology company, provides the first service that demonstrably measures ad viewability across all major browsers, ad exchanges, ad networks and ad servers, even when the ad impressions are served in unfriendly (cross-domain) iframes. In particular, spider.io’s technology is the first to be able to measure the viewability of iframed ads across Chrome and Safari browsers.
According to Dr Douglas de Jager, CEO of spider.io: “In an industry of smoke and mirrors, we aim to be transparent. We have built the industry’s first comprehensive viewability measurement technology and we encourage all prospective partners to confirm our bold claim for themselves. Testing can typically be wrapped up within the day.” 
It has been suggested that 40–70% of display ad impressions are typically delivered in cross-domain iframes. [2, 3] An unfriendly or cross-domain iframe is an iframe served from a different domain to the host website. Due to a browser security policy, termed the same origin policy, , web browsers do not allow communication between webpages and iframes served from different domains. This means that any script which is included to measure the viewability of an ad impression from within a cross-domain iframe cannot ordinarily access either the position of the iframe relative to the host webpage or the scroll offset of the browser window relative to the host webpage. This poses a significant challenge for those attempting to measure viewability from within cross-domain iframes.
spider.io is currently engaged in the MRC’s accreditation process for the company’s comprehensive ad viewability technology. Additionally, spider.io is working with several of the leading exchanges, ad networks, DSPs and retargeters to provide analogous viewability measurement across their display ad inventory.
For those who wish to find our more about display ads viewability, we recommend the seminal white paper written by Dr Douglas de Jager and Dr Simon Overell, both of spider.io, titled “Verifying the Visibility of Display Ads Served within Cross-Domain Iframes.” This white paper surveys the approaches taken within the industry to the problem of cross-domain iframes—providing a survey of patent applications, press releases and publicity material together with a deconstruction of visibility-verification code where available. 
spider.io is a London-based technology company which identifies when display ads are legitimately seen by human visitors.
spider.io distinguishes when human website visitors are interacting legitimately with web content from other types of visitor interaction with web content—often by automated or systematic visitors and also often as a result of deviant publisher activity. When a human visitor is legitimately accessing content through a web browser, spider.io also accurately identifies when content is viewable within the browser’s viewport.
[1.] A demonstration of the testing process can be seen at http://spider.io/vSta98h]
 This white paper is available upon request.