Island raises $400m at a $6.4bn valuation to govern AI agents

Island, the Dallas company behind the Enterprise Browser, has raised $400m in a Series F round. The deal values it at $6.4bn, Island announced on Thursday. Evolution Equity Partners led the round.

In March 2025, Island raised $250m in a Series E led by Coatue, at a $4.8bn valuation. The company now pitches itself as a control layer for both employees and AI agents, not only as a browser.

Growth and investors

Island has 1,000 employees. It has doubled its annual recurring revenue (ARR) every fiscal year since its 2022 launch, the company said, but it gave no figure. Calcalist’s CTech reported that ARR is about $200m. It also reported that Island had more than 500 staff a year ago.

Existing investors Prysm Capital, Sequoia Capital, Coatue, Cyberstarts, Insight Partners, J.P. Morgan Growth Equity Partners, Alta Park Capital, Georgian, G Squared and Squarepoint joined the round. CrowdStrike co-founder Dmitri Alperovitch made another personal investment.

“We’ve entered a new era in which people and AI agents work side by side. Just like humans, agents need the right context, access, guardrails, and accountability to succeed,” said Mike Fey, Island’s chief executive and co-founder.

From browser to agents

Island started with a browser that builds company security controls into the place where most office work happens. It then added data loss prevention and network security. It now also offers an extension for consumer browsers.

Its newest pitch is governance for AI agents. One policy engine and one audit trail now cover browsers, devices, apps, networks and data, the company said. Its Enterprise AI product adds identity controls, guardrails, human approvals and cost limits for agents. It works whichever AI models a customer picks.

“Agents do not operate in a single layer of the technology stack, so they cannot be governed from one,” said Dan Amiga, Island’s chief technology officer and co-founder.

Richard Seewald, founder of Evolution Equity Partners, said Island can see and govern what people and agents do. That holds wherever they use applications and data, he said.

A crowded field

Island is not alone in selling security for AI agents. Neo came out of stealth in July with $100m to build a control layer for agents. Cloudflare has launched a browser for AI agents, and Anthropic has added data loss prevention hooks to Claude Enterprise.

Palo Alto Networks also sells an enterprise browser. It bought Israeli start-up Talon in 2023, then offered its own enterprise browser free to qualified customers of its network security service.