DoubleVerify, a company that tracks online ad placement, has raised $10 million in second round funding.

Given the importance of online advertisements as a key source of revenue on the web, it’s also important to make sure that the ads are getting served correctly. DoubleVerify’s ad verification service does just that, and allows those in the ad supply chain — including publishers, marketers, agencies, and ad networks — to better keep track of individual ads.

We’ve previously covered the launch of DoubleVerify’s realtime ad verification service, which crawls websites and automatically captures screenshots of offending ad placement. The real-time verification service said its technology is effective: Among sites that demonstrated 10 to 30 percent of ads that didn’t meet buyer’s specifications — including one that was off by a massive 70 percent — DoubleVerify was able to reduce those numbers to zero after notifying the offending sites and the ad agency behind the ads.

The company’s competitors include Collective and AdXpose. Its co-founder and CEO Oren Netzer says that DoubleVerify differs from the rest because it is more comprehensive.

Notably, the company’s service can see ads through nested IFrames — a coding technique which makes ads appear as if they are being delivered from a different page. Some 70 percent of online ad impressions are delivered via nested IFrames, and DoubleVerify tells us it’s the only ad verification company which can properly track those ads. It’s competitors, of course, take issue with that claim: A representative from AdXpose tells us that its product can also see through IFRAMES.

The company currently tracks more than 25 billion ads per month — a multiple of what its competitors verify combined. Its customers include over 50 Fortune 500 marketers.

DoubleVerify’s second round of funding was led by Institutional Venture Partners. It previously raised raised $3.5 million in funding from Blumberg CapitalFirst Round Capital, Genacast Ventures, and individual investors.