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.
Elliott Robinson & Andrew Ren
Published on Nov 19, 2025
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.
Contributors
Elliott Robinson
Partner
Elliott Robinson is based in the NYC office and a partner of the growth investment practice at Bessemer, where he focuses primarily on Cloud software investments. He co-authors Bessemer’s iconic 10 Laws of Cloud Computing and the annual State of the Cloud Report. He looks to partner with companies and management teams that are defining their market category while also maintaining a set of core values that will allow them to expand and solidify their leadership position. Elliott is currently a board member for Coactive AI, Databook, Hinge Health, Hyperscience, Imply Data, Netlify and Render. Additionally, he has led Bessemer’s investments in Forter, Statespace, and Canva.
Prior to joining Bessemer, Elliott was a partner with M12, leading investments in companies such as Livongo (IPO: LVGO), BlueVine, Trusona, and Cooler Screens. Elliott started his career with Syncom Venture Partners, investing in both early and growth stage enterprise software and frontier tech companies such as CLEAR and Iridium Communications (IPO: IRDM). After six years with Syncom, he joined Georgian Partners, investing in a number of successful growth stage software companies such as TurnItIn (acquired by Advance), Kinnser (acquired by Mediware), and eSentire.
Elliott earned his M.B.A from Columbia Business School and a Bachelor of Science in mathematics from Morehouse College. He is a board director of Venture Forward, BLCK VC, and a member of the Kauffman Fellows Class 22.
Andrew Ren
Investor
Andrew is an investor with Bessemer's growth investment practice in NYC, where he primarily focuses on AI and cloud software investments.
Prior to joining Bessemer, Andrew was an investor in Carlyle's US Buyout fund, where he evaluated consumer, media, and retail businesses. Andrew started his career as an investment banker at Moelis & Company in the M&A and restructuring group.
Andrew earned his MBA from The Wharton School and B.S. from Boston University. In his spare time, he enjoys tilting over bullet chess, exploring industrial techno, and advocating for incarceration reform.
