We’ve raised $9.2 million led by Index Ventures

In 2015, Sebastian and I created Castle with a simple vision. We saw that it was increasingly difficult for companies to access their online accounts and keep their users safe. We also saw that consumers were being asked again and again to take responsibility for their security through robust passwords and other security measures.

We started Castle because we wanted to figure out a way to shift security responsibility from end users to the companies who serve them. In those early days as two engineers in Sweden, we recognized that there was an opportunity to turn every online company into a security guardian who could keep their users safe.

Today, we’re well on our way to making that dream a reality. Our team is making available best practices employed today only by tech giants like Google, Amazon, and Apple. These companies rely on identity teams to track security issues in real-time and can detect if a consumer is likely to be on vacation, or whether the login is truly out of the ordinary, and can alert users accordingly. Although these tech giants do a great job, their capabilities aren’t available to other companies.

Whether our customers are building a bitcoin service, e-commerce store, or mobile app, Castle’s developer APIs deliver a fully automated approach to account security. We help you protect your users from automated credential stuffing attacks and human-powered account takeovers. And the more users we serve, the better our algorithms get at catching the bad guys. Our vision is that one day, users around the world won’t need passwords anymore.

Our models, driven by end user behavior and feedback, offer a unique and innovative approach, as they’re continuously updated, in real-time, based on how users use apps and reset passwords. Castle’s secret sauce doesn’t lie in the use of machine learning per se, but its models are driven by end-user behavior and feedback exclusively. Unlike other solutions, there’s no need for supervision from a security team.

We’re pleased to announce that we’ve raised $9.2M in Series A funding from Index Ventures, with participation from existing investors Y Combinator, First Round Capital, and F-Prime Capital Partners. Angel investors joining the round include Zack Urlocker, former COO at Duo Security, René Bonvanie, CMO at Palo Alto Networks, and Olivier Pomel, CEO at Datadog. This round brings Castle’s total funding to $11.6M. Shardul Shah, partner at Index Ventures will join the board of directors following the announcement.

We want to enable companies to make qualified decisions about security. At every point, we want to help companies reduce friction for their users, so that security is embedded into the overall user experience. To do that, companies need to have a deep understanding of how users react to different security measures. Castle provides that insight.

We’re proud to be fulfilling our initial vision, and are excited to have such knowledgeable investors on board. We expect to accelerate our growth in the next several months and coming years. We’re hiring for a multitude of positions and will be expanding our offices in San Francisco, Malmo, and Cracow.