Armadin raises $255.5M for autonomous security testing

Armadin announced on October 1 that it raised $255.5 million in Series B funding, bringing total funding to $445 million and valuing the company above $2.5 billion. The company said Andreessen Horowitz and Accel co-led the round. Its platform runs agentic attack campaigns intended to find and close vulnerabilities for customers.

The maker signal is a growing budget for continuous security testing as agent capabilities improve. Funding does not prove that an autonomous attack system finds every weakness or that customers can safely grant it broad access. It shows investors see a large problem around fast-changing attack surfaces.

If you test an agentic security tool, isolate it from production first. Define allowed targets, evidence requirements, stop conditions, and human approval, then measure useful findings, false positives, repair time, and the cost of each accepted result.