Sift Science, a San Francisco company that builds software to fight fraud online and recently opened a Seattle office, has raised a massive $53 million funding round. The round is led by New York equity firm Stripes Group and investors include heavily funded Seattle startup Remitly. The investment doubles Sift's lifetime funding to $107 million. Some big-name customers like Airbnb, Zillow, and OpenTable, use Sift Science to identify bad actors by flagging risky or abusive behaviors before they commit fraud. The software helps e-commerce companies and other online brands reduce chargebacks, fraudulent transactions, and account abuse.