Doubling down on Doppel: the future of AI-native social engineering defense
Bessemer Venture Partners leads Doppel’s $70M Series C just six months after leading their Series B, as the team develops the social engineering defense system built on OpenAI’s latest models.
When Bessemer first partnered with Doppel and led the team’s Series B just under six months ago, what originally stood out to us was the team’s incredible ambition, rapid iteration, and laser focus — all of which were crucial for the sensitive nature of where they were building. As we navigate this unique moment in cybersecurity, where criminals are armed with generative AI to execute hyper-personalized, sophisticated attacks, Doppel is fighting fire with fire using AI to address these social engineering threats.
We’re doubling down on our investment in Doppel to accelerate product innovation across their existing digital risk protection product portfolio, as well as in new products such as the real-time threat graph and human risk management offerings — including phishing simulation and security awareness training. By using agentic AI built on OpenAI’s latest GPT-5 model and reinforcement fine-tuning (RFT) techniques (as featured on OpenAI’s API stories), Doppel prevents digital infiltration and enforces takedowns. The company’s momentum is undeniable, with a record ARR growth that has tripled year-over-year. The AI-powered platform now has over 200 customers and has increased its presence fivefold across Fortune 500 customers.
Over the past six months, Doppel has closely monitored advances in AI models to understand how they reshape the threat landscape. Drawing on data from its customers and internal threat research, the company has observed a sharp rise in the volume, speed, and complexity of attacks. At the same time, Doppel’s hands-on experimentation with new foundational models has uncovered major insights into how emerging technologies can be used defensively. This research has been especially influential in the development of Doppel’s latest “vibe-phishing” simulation product, designed to address the growing sophistication of deepfake-based real-time social engineering threats.
This is why we’re leading Doppel’s $70 million Series C — underlining our support of co-founders Kevin Tian (CEO) and Rahul Madduluri (CTO) on their mission to protect the world from the deluge of social engineering attacks. To learn more about Doppel and where they’re headed, or to join their team in building the future of AI-native cybersecurity, visit their website.
