The AI red-teaming tool OpenAI had to buy.
Open-source CLI for systematic LLM security testing. 350K developers. 127 Fortune 500 companies. Acquired by OpenAI March 2026.
| Industry | AI & Machine Learning |
| Type | Tech Startup |
| Size | Startup (1-50) |
| Founded | 2024 |
| Funding | |
| Stage | Series A |
| Valuation | $86M |
| Raised | $23.4M |
| Lead investors | Insight PartnersAndreessen Horowitz |
| Website | Visit Promptfoo |
Where Promptfoo sits against the other names we cover on this beat. Each line is that company’s verdict, not a summary of it.
The 2026-07-30 print settled four of the five questions the prior dossier said it could
Cash $78.2B
The bear case arrived a year early and the bull case grew a new leg in the same quarter
Cash $90.3B
The buildout stopped being paid for by the ad business and started being paid for by the capital markets
Cash $90.3B
NOT ASSESSED — this is a pre-print evidence refresh, not a call.
A genuinely great business priced as a perfect one