TLDR: Promptfoo Inc., a leader in AI evaluation and testing, has successfully raised $18.4 million in early-stage funding. This investment, led by Insight Partners with participation from Andreessen Horowitz, will fuel the development of its AI security and evaluation platform, addressing critical vulnerabilities in large language models.
Promptfoo Inc., a prominent open-source framework for artificial intelligence evaluation and testing, announced on July 29, 2025, that it has secured $18.4 million in an early-stage funding round. The Series A investment was spearheaded by global software investor Insight Partners, with existing investor Andreessen Horowitz also participating.
Founded in 2024, Promptfoo has rapidly established itself as a crucial solution for AI security. The company provides robust AI security testing and risk management services, incorporating industry standards such as red teaming, guardrails, and continuous monitoring. Red teaming, a practice originating from cybersecurity, involves simulating adversarial attacks against AI applications and models to identify vulnerabilities. This proactive approach extends beyond traditional testing, evaluating various components of the AI stack, including model behavior, data pipelines, and user interactions. The goal is to develop more effective guardrails and smarter defenses against sophisticated attacks.
The funding comes at a critical time, as the rapid adoption of generative AI has outpaced traditional cybersecurity measures, creating new vulnerabilities, particularly for large language models (LLMs). Promptfoo’s data indicates that a significant 82% of AI-related security issues in Fortune 500 companies go undetected by standard runtime ‘guardrails.’ Furthermore, despite companies investing over 650 hours in manual testing per product release, they often cover less than 5% of critical threats like prompt injection, data leakage, and policy evasion.
Promptfoo’s open-source AI red-teaming and security testing framework is currently utilized by over 125,000 developers worldwide. Additionally, more than 30 Fortune 500 companies leverage its commercial platform to safeguard AI systems across diverse sectors, including retail, telecommunications, and finance. By integrating automated vulnerability detection, reproduction, and remediation into the software development lifecycle, Promptfoo empowers organizations to confidently expand complex AI deployments while protecting sensitive data and brand reputation.
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Ian Webster, CEO and co-founder of Promptfoo, highlighted the evolving landscape, stating, ‘The internet is being rebuilt for agents and the APIs they call are increasingly being exposed as Model Context Protocol servers.’ He added that this coincides with a shift from single-turn text to more complex interactions, underscoring the growing need for robust AI security solutions.
