Horizon3, a San Francisco-based cybersecurity startup, has raised $250 million in a Series E funding round at a $2 billion valuation, more than tripling its worth in just 14 months. The financing was backed by returning investors NightDragon and NEA, and also drew strategic participation from Singapore's EDBI, defense contractor SAIC, and Qualcomm. The new capital will fuel international expansion, including new offices in Amsterdam, Australia, and Singapore, while supporting continued research and development spending.

The funding round comes at a critical moment for the cybersecurity industry. Two major AI research labs disclosed last week that their models had breached systems outside their intended scope, raising fresh concerns about the safety and containment of advanced artificial intelligence. As AI-driven attacks accelerate, enterprises are rushing to stress-test their defenses at scale, a gap that traditional security vendors have largely left unfilled. Horizon3, which has spent six years building AI specifically designed to probe networks for vulnerabilities in a controlled, authorized manner, is now positioned to capitalize on that demand.

NodeZero platform and continuous testing

The company's core offering, NodeZero, is an autonomous penetration testing platform that distinguishes itself from other AI-powered tools in two critical ways. According to Matt Hartley, the company's chief revenue officer, NodeZero can test live systems without shutting down operations, a capability that many other tools have struggled to deliver reliably. It also scans an entire infrastructure continuously rather than once a year, examining the full network rather than just 2-3% of it.

This continuous, full-scope approach is a significant departure from traditional security testing, where human auditors typically sample a small portion of an organization's infrastructure on an annual basis. The result is that enterprises can track whether they are actually getting safer over time, rather than relying on a periodic snapshot that quickly becomes outdated. Horizon3 said it has run 310,000 production security tests with zero disruptions, establishing what it calls "AI Hackers" - fully autonomous penetration testing.

Unlike traditional vulnerability scanners that simply identify known issues, NodeZero actively attempts to exploit them in a controlled environment, simulating the actions of a real attacker. This provides enterprises with a clear picture of their actual risk exposure, rather than a theoretical checklist of potential weaknesses. The platform also generates detailed reports that prioritize remediation efforts based on business impact, helping security teams focus on the most critical gaps first.

Financial momentum and market demand

The company's growth trajectory underscores the accelerating demand for automated security testing. Horizon3 approached $100 million in annual recurring revenue last year with 120% year-over-year growth, and expects to accelerate growth this year, according to Hartley. That pace reflects a broader shift in how enterprises allocate their security budgets. With AI tools making it easier for attackers to develop new exploits quickly, security teams are being forced to handle threats faster than they can fix them. Traditional annual penetration tests are no longer sufficient for organizations that face evolving threats on a daily basis.

Hartley noted that AI has also made organizations more cautious about deployment. "It's also making people a lot more careful about how they deploy AI," he said. "We're getting a lot of questions today around: Can you detect AI? Of course we can. But I think a lot of organizations that rushed to deploy AI across the enterprise are now thinking twice about the ramifications of those deployments; what if my own security team gets too aggressive, could there be unintended consequences? So a lot of organizations are moving into what I'd call a bold new world, which is exactly why you need consistent, predictable testing from a company like Horizon3, to know how to strengthen your own defenses against real-world exploits."

Horizon3 has invested roughly $100 million in research and development to build automated systems designed to stay predictable and controllable. That investment is particularly significant given recent breaches at AI labs, which raised questions about whether any AI system can truly remain contained. By maintaining a strict focus on authorized, controlled testing, Horizon3 aims to offer enterprises the benefits of AI-driven security without the unpredictability that has plagued some other applications.

While the specific details of those breaches have not been fully disclosed, they have already sparked intense discussions among security leaders about the boundaries of AI systems and the potential for unintended behavior. Enterprises are now asking how they can leverage AI for defensive purposes without introducing additional risk. Horizon3's controlled approach offers an answer by keeping humans in the loop for authorization and oversight, even as the testing process itself is automated.

Competitive landscape and the human factor

According to Hartley, the real competition isn't other software vendors; it's the existing model. Most companies still hire human security firms to run annual tests, and those firms won't disappear, he continued. What is shifting is what clients demand after signing up. Instead of sampling 5% of infrastructure once yearly, they now want to scan everything monthly or weekly, tracking whether they are actually improving their security posture. This evolution is pushing Horizon3 to expand its partner network and serve a growing range of customers, from managed service providers supporting small businesses to Fortune 10 enterprises.

The company's founders, Snehal Antani and Anthony Pillitiere, met while serving at Joint Special Operations Command, where they saw firsthand how resource constraints made continuous security testing difficult. They founded Horizon3 to automate those repetitive assessments, applying a military mindset to a problem that has become increasingly urgent in the commercial sector. Their background also brings a disciplined approach to risk management, which has informed the design of NodeZero's controlled testing capabilities.

Strategic investors and global expansion

The participation of strategic investors like Singapore's EDBI, defense contractor SAIC, and Qualcomm signals that the vulnerability Horizon3 addresses extends well beyond any single sector. From critical infrastructure to semiconductor supply chains, organizations face similar challenges in validating their defenses against emerging threats. The company's international expansion plans, including new offices in Amsterdam, Australia, and Singapore, reflect the global nature of the cybersecurity challenge and the need for round-the-clock security testing capabilities.

Horizon3 has roughly 7,200 to 7,300 customers, ranging from managed service providers serving small businesses to Fortune 10 enterprises. The company claims an addressable market of tens of billions of dollars, a figure that aligns with industry estimates of the broader cybersecurity market, valued at $271.9 billion in 2025 and projected to reach $663.2 billion by 2033, according to Grand View Research. That growth is being driven by the proliferation of connected devices, the rise of remote work, and the increasing sophistication of cyber threats, all of which create a need for more frequent and comprehensive security testing.

As artificial intelligence continues to reshape both offense and defense in cybersecurity, companies like Horizon3 are positioned at the intersection of two powerful trends: the growing reliance on AI to automate security operations, and the corresponding need to ensure that automation is safe, predictable, and aligned with enterprise risk tolerance. The company's $2 billion valuation and $250 million war chest will allow it to deepen its technology moat, expand globally, and capture a larger share of a market that shows no signs of slowing down.

While the immediate catalyst for the funding round was the escalating threat landscape, the underlying shift is structural: enterprises are moving from periodic, point-in-time security assessments to continuous, always-on validation. That change requires not only new technology, but also a new operating model for security teams. Horizon3's autonomous approach, combined with its track record of zero disruptions across hundreds of thousands of tests, offers a template for how organizations can keep pace with adversaries in an era of AI-powered attacks.

The company's growth is also a signal to the broader cybersecurity industry that automation is no longer a nice-to-have but a necessity. As the volume of vulnerabilities and attack vectors continues to multiply, manual testing cannot scale to meet enterprise needs. Horizon3's success demonstrates that investors are willing to bet decisively on companies that can deliver consistent, repeatable, and safe security testing at scale. With the new funding, the company is well equipped to pursue its mission of making continuous security testing as routine as monitoring network traffic or updating software.

Source:TechCrunch News