• by Tyler Loechner  @mp_tyler, June 30, 2015

Distil Networks, a bot detection firm headquartered in Arlington, VA., on Tuesday announced it has closed a $21 million Series B round of funding led by Bessemer Venture Partners.

Other participants include current investors Foundry, TechStars, ff Venture Capital, Idea Fund and Correlation Ventures.

Distil says its technology builds a “signature” for every Web request, and those signatures are tied to a unique “fingerprint.” Distil says it can block suspicious “fingerprints” across its portfolio of clients, which includes brands such as Glassdoor, CrunchBase, Wayfair and others.

Fraud is an everpresent problem for marketers, but it’s one they are actively attempting to tackle. Distil’s round of funding is just the latest in a string of recent news items that all revolve around curbing digital ad fraud. 

“Malicious bots have become increasingly more pervasive, sophisticated and detrimental to companies around the world,” stated Rami Essaid, CEO and co-founder of Distil Networks.

David Cowan, partner at Bessemer, will join Distil’s board of directors. Cowan is now intertwined with a handful of “Web quality” companies -- in addition to serving on Distil’s board, Cowan is co-founder of Verisign, Good Technology and Defense.net.

Distil has now raised a total of $38 million to date, per a release. The latest round will be used to improve the company’s bot detection and mitigation technology.