D is a German corporation with its principal place of business in Kassel, Germany. D runs a 'self-service platform' that helps customers build better software. D brings its customers' code from a third-party hosting service like GitHub to its 'controlled cloud environment,' where it runs 'software analysis tools' meant to 'improve source-code quality, eliminate bugs, and find security vulnerabilities.' D offers a fourteen-day free trial. D employs Google Analytics. Customers pay only in euros. D's contract contains a forum-selection clause and a choice-of-law clause that provide that all lawsuits relating to the contract be brought in German courts and under German law. D has no U.S. office, phone number, or agent for service of process. D directs no advertising at the United States; and its employees do not go to the United States on business. Customers can use the service 'anywhere where Internet access is available.' D is 'trusted by over 5000 projects and companies around the world.' From January 2014 to June 2017 D sold its services to 156 U.S. customers located in thirty states. The revenue was just under $200,000 in June 2017. The record does not reveal what percentage of D's total revenue comes from the United States. D had two Maine customers, who collectively paid €3,100 for the services. Plixer International, Inc. (P), a Maine corporation, sued D in federal district court in Maine on November 21, 2016, for trademark infringement. P owns the registered mark 'Scrutinizer.' P filed for the mark in July 2015 but used the mark as early as November 2005. That application covered 'computer software and hardware for analyzing, reporting and responding to malware infections and application performance problems, used in the field of information technology.' P alleged D caused 'confusion, mistake or deception as to the source' of D's services; that the use 'will infringe and/or dilute P's prior rights' in the mark; that the use 'will interfere with P's use' of its mark; and that D's 'services are closely related to the services covered by P's' mark, so 'the public is likely to be confused. P claimed that D's Scrutinizer's nationwide contacts with the United States supported specific jurisdiction under Federal Rule of Civil Procedure 4(k)(2). In January 2017, D filed a U.S. trademark application for 'Scrutinizer.' The court held that D 'operated a highly interactive website that sold its cloud-based services directly through the website, that it was open to business throughout the world, that it accepted recurrent business from the United States in a substantial amount, and that it did so knowingly.' The court found purposeful availment. D appealed. In its holding, it found in part that D’s application for a trademark confirmed D’s desire to deal with the American market.