OpenAI to buy cybersecurity startup Promptfoo to better safeguard AI agents

OpenAI said Monday that it is acquiring the cybersecurity startup Promptfoo, which provides tools to help safeguard and test complex artificial intelligence systems.

The Sam Altman-led firm did not disclose the terms of the deal, but said Promptfoo’s team would join OpenAI. Promptfoo’s security tools will be brought within OpenAI’s Frontier platform for AI agents.

“As AI agents become more connected to real data and systems, securing and validating them is more challenging and important than ever,” Promptfoo CEO Ian Webster said in a statement. “Joining OpenAI lets us accelerate this work, bringing stronger security, safety, and governance capabilities to the teams building real-world AI systems.”

OpenAI said that it would also continue building Promptfoo’s popular open-source project that lets developers test various AI-related prompts and agents and compare the performance of large language models like GPT, Anthropic‘s Claude and Google‘s Gemini.

Promptfoo announced in July that it had raised a Series A financing round of $18.4 million, which was led by Insight Partners and also included Andreessen Horowitz.

The startup has 11 employees and has raised a total of $22.68 million with a post-valuation of $85.50 million as of July 2025, according to the deal-tracking service Pitchbook.

Andreessen Horowitz has been pushing into the infrastructure and defense markets, and most recently said in January that it raised $15 billion as part of its funding efforts related to “American Dynamism.”

From that raise, the venture capital firm said that $6.75 billion will be allocated for a growth fund while two other $1.7 billion funds will focus on apps and infrastructure, respectively.

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