Founded in 2009 as AdSafe Media, IAS works with companies such as Verizon Communications Inc., HP Inc. and Citibank to help prove that their digital ads are viewable, meaning they aren’t running on parts of websites that can’t be seen.

The company also helps marketers ensure their ads aren’t running on sites with objectionable content.

IAS touts about 600 employees in various markets, with more than $140 million in revenue, according to a person close to the company.

IAS investors include Sapphire Ventures, Pelion Venture Partners, August Capital and Accomplice.