AI security startup Promptfoo today announced raising $18.4 million in a Series A funding round that brings the total raised by the company to $23.4 million.
The new investment round was led by Insight Partners, with additional support from previous investor Andreessen Horowitz.
Founded in 2024, San Francisco, CA-based Promptfoo has built a platform that helps organizations and developers secure LLMs and generative AI applications through detecting and addressing risks such as prompt injections, jailbreaks, data leaks, and generation of harmful content.
The solution embeds automated red-team tests into the build and release processes, provides actionable guidance for the identified issues, and feeds the results into the organization’s existing vulnerability management workflows.
The startup’s platform generates attacks tailored to each organization, on-the-fly, to identify specific vulnerabilities that could allow attackers to steal documents, override system prompts, access restricted resources, or discover AI system capabilities and integrations.
Through end-to-end automation, Promptfoo’s platform helps security teams harden complex agentic systems using a single, continuous workflow, so that organizations can deploy AI securely at scale.
According to Promptfoo, its solutions have been adopted by financial institutions, retailers, and telecommunication providers. Its open source tools are used by more than 100,000 developers, and have been adopted by nearly 30 Fortune 500 companies, the startup says.
The new funding will allow Promptfoo to scale its teams and accelerate the development of its platform.
“AI security has become the largest blocker to enterprises shipping generative AI applications to end users. Architectures like RAG, agents, and most recently MCP have expanded what’s possible with AI, but they’ve dramatically increased the attack surface,” Promptfoo CEO and co-founder Ian Webster said.
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