Promptfoo, an open-source toolkit for systematic and measurable prompt engineering, has surpassed 100,000 users, reflecting its widespread adoption by developers, enterprises, and AI enthusiasts. Founded by Ian Webster and Michael D'Angelo, Promptfoo addresses the need for reliable AI application development through tools that evaluate model prompts and identify vulnerabilities via AI red teaming. The framework has expanded to support AI agents and multi-agent systems, offering specialized tools to test complex interactions to ensure safety and consistency. Industry recognition has been marked by integrations with platforms like OpenAI, AWS, and IBM, which feature Promptfoo in educational materials. Trusted by individual developers and Fortune 500 companies alike, the platform allows users to test prompts across various LLM providers, detect vulnerabilities, benchmark models, and integrate security testing into CI/CD pipelines. As Promptfoo continues to grow, it aims to democratize AI security and enhance its capabilities to meet the evolving needs of its community.