Get to Know Us

Horizon3.ai is a fast-growing, remote cybersecurity company dedicated to the mission of enabling organizations to proactively find, fix and verify exploitable attack vectors before criminals exploit them. Our flagship product, the NodeZeroTM platform, delivers production-safe autonomous pentests and other key assessment operations that scale across the largest internal, external, cloud, and hybrid cloud environments. NodeZero has been adopted by organizations of all sizes, from small educational institutions to government agencies and Global 100 enterprises. It is used by IT Ops/SecOps teams, consulting pentesters, and MSSPs and MSPs.

We are a fusion of former U.S. Special Operations cyber operators, startup engineers & operators, and formerly frustrated cybersecurity practitioners. We're committed to helping solve our common security problems: ineffective security tools and false positives, resulting in alert fatigue, blind spots, "checkbox” security culture, cybersecurity skills shortage, and the long lead time and expense of hiring outside consultants. Collectively, we are a team of learn-it-alls, committed to a culture of respect, collaboration, ownership, and results.

What You’ll Do

We are seeking a motivated Mid to Senior Level Enterprise Technical Support Engineer with 5+ years of hands-on industry experience to join our high-performing support team. In this role, you will serve as a key technical resource for our enterprise customers, diagnosing and resolving complex issues related to cloud infrastructure, networking, and security. You'll collaborate with cross-functional teams to ensure seamless customer experiences, leveraging your expertise in Linux, containerization, and cloud technologies. This position requires a proactive self-learner who thrives in fast-paced enterprise environments and can handle escalated support tickets with minimal supervision.

Key Responsibilities

Provide advanced technical support to enterprise customers via phone, email, chat, and remote sessions, troubleshooting issues across cloud, networking, and infrastructure domains.
Diagnose and resolve customer-reported problems, performing root cause analysis to prevent recurrence and ensure high availability of services.
Collaborate with engineering, product, and sales teams to escalate and resolve intricate technical challenges, while documenting solutions for knowledge sharing.
Assist in the deployment and optimization of customer environments, offering guidance on best practices for infrastructure as code (IaC) and containerized applications.
Monitor and respond to support tickets in a timely manner, maintaining SLAs and contributing to continuous improvement of support processes.
Mentor junior team members and contribute to internal training resources, fostering a culture of knowledge transfer and technical excellence.
Stay abreast of emerging technologies and industry trends to enhance support capabilities and customer satisfaction.

Required Qualifications

Bachelor's degree in Computer Science, Information Technology, Engineering, or a related field (or equivalent professional experience).
5+ years of relevant industry experience in technical support, systems administration, or cloud operations, ideally in an enterprise-level environment (e.g., supporting large-scale deployments for Fortune 500 clients).
Background in cybersecurity, including knowledge of threat detection, vulnerability management, encryption standards, and compliance frameworks (e.g., SOC 2, GDPR).
Strong proficiency in Linux administration, including server configuration, performance tuning, security hardening, and troubleshooting in production environments.
Hands-on experience with Docker and containerization technologies, such as building, deploying, and managing containerized applications in orchestrated environments (e.g., Kubernetes or similar).
Solid understanding of cloud platforms (e.g., AWS, Azure, or GCP) and Infrastructure as Code (IaC) tools like Terraform, Ansible, or CloudFormation, with experience provisioning and managing cloud resources.
In-depth knowledge of networking fundamentals, including TCP/IP, firewalls, VPNs, load balancers, and network troubleshooting tools (e.g., Wireshark, tcpdump).
Basic scripting skills in languages such as Bash, Python, or PowerShell for automation of routine tasks, diagnostics, and simple workflow enhancements.
Demonstrated self-learning ability, evidenced by personal projects, home labs, certifications (e.g., AWS Certified Solutions Architect, Linux+, or equivalent), or contributions to open-source communities, with a track record of adapting to new technologies independently.
Experience equivalent to a junior cloud administrator role in an enterprise setting, managing multi-tenant environments, resource allocation, and compliance requirements.
Familiarity with identity management systems, including Role-Based Access Control (RBAC), Single Sign-On (SSO) protocols (e.g., OAuth, SAML), and directory services (e.g., Active Directory, LDAP).
Basic understanding of database concepts, including relational and schemaless databases (e.g., SQL vs. NoSQL), schema design, querying, and basic administration tasks.

Preferred Qualifications

Proven experience integrating and troubleshooting APIs, including RESTful services, authentication mechanisms, and API-driven automations in enterprise applications.
Familiarity with observability tools like Datadog, including monitoring, logging, and alerting for distributed systems to enhance system reliability and performance.
Basic experience with managed database services such as Amazon RDS, including setup, backups, scaling, and query optimization.
Full-stack coding proficiency in languages like Python, JavaScript, or Go, with experience developing custom tools or scripts for support automation.

Travel Required

We are ideally looking for someone to be based hybrid in our Amsterdam office or can be remote in UK, France, Ireland or Spain.

Compensation and Values

At Horizon3, we believe that our people are our greatest asset, and our compensation philosophy reflects this core value. We are committed to fostering an environment where all employees feel valued, respected, and rewarded for their contributions. Our compensation structure is designed to be fair, competitive, and transparent, ensuring that every team member is recognized and compensated equitably across roles, levels, and locations.

Additional compensation: All full-time roles are eligible for an equity package in the form of stock options.

Perks of Horizon3.ai

Inclusive Team: We value diversity and promote an inclusive culture where everyone can thrive.
Growth Opportunities: Be part of a dynamic and growing team with numerous career development opportunities.
Innovative Culture: Work in a collaborative environment that encourages creativity and out-of-the-box thinking.
Competitive Compensation: We offer competitive salary, equity and benefits. Our benefits include health, vision & dental insurance for you and your family, a flexible vacation policy, and generous parental leave.

You Belong Here

Horizon3 is not just an equal opportunity employer - we are a community that values diversity, equity, and inclusion as fundamental principles of our culture and success. We are dedicated to fostering a workplace where everyone feels welcome and respected, regardless of race, color, religion, sex, national origin, age, disability, veteran status, sexual orientation, gender identity or expression, genetic information, marital status, hair length or any other legally protected status by law.

Our commitment to diversity and inclusion means we strive to attract, develop, and retain a workforce that reflects the varied communities we serve. We believe that diverse perspectives drive innovation and strengthen our ability to create cutting-edge cybersecurity solutions. At Horizon3, every team member is valued and supported in an environment that encourages personal and professional growth.

We welcome candidates from all backgrounds and experiences, and we encourage all qualified individuals to apply. Come be a part of Horizon3, where your unique contributions are recognized, and your potential is limitless.

Other Duties

Please note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities that are required of the employee. Duties, responsibilities, and activities may change at any time with or without notice.

Application Note

In any materials you submit, you may redact or remove age-identifying information such as age, date of birth, or dates of school attendance or graduation. You will not be penalized for redacting or removing this information.

About the company

Horizon3.ai specializes in cybersecurity by offering NodeZero, a SaaS platform for autonomous penetration testing. It lets enterprises simulate cyber-attacks on their own systems in a self-service way, without installing persistent agents, and without ongoing human intervention. The platform works by running security-focused attack simulations in production environments to uncover exploitable vulnerabilities and weak controls, delivering vulnerability assessments, threat simulations, and compliance-oriented testing through tiered subscription plans. This approach differentiates Horizon3.ai from traditional pentesting by being self-service, agentless, and safe to run in live environments, while targeting enterprise customers that must meet standards such as PCI DSS. The company aims to help organizations improve their security posture, prioritize remediation, and maintain regulatory compliance by continuously identifying and fixing weaknesses.

Company Size

501-1,000

Company Stage

Series E

Total Funding

$437M

Headquarters

San Francisco, California

Founded

2019

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Simplify's Take

What believers are saying

August 3, 2026 Series E raised $250 million at over $2 billion valuation.
September 15, 2026 CrowdStrike SIEM integration pushes NodeZero findings into mainstream security operations.
August 2026 Australia sovereign instance and federal hiring expand Horizon3 into regulated, higher-budget markets.

What critics are saying

Pentera and XBOW pressure Horizon3’s pricing and differentiation as autonomous pentesting commoditizes.
Customer trust collapses after one production outage or false exploit path during testing.
Deloitte, CrowdStrike, and WWT can absorb Horizon3 into broader platforms, weakening standalone demand.

What makes Horizon3.ai unique

NodeZero runs production-safe autonomous pentests without persistent agents, unlike consultant-led annual testing.
Horizon3 sells continuous attacker-perspective validation across identity, cloud, web, and on-prem surfaces.
FedRAMP High authorization and sovereign instances differentiate Horizon3 for government and regulated buyers.

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Benefits

Health Insurance
Vision Insurance
Dental Insurance
Unlimited Paid Time Off
Remote Work Options
Stock Options

Growth & Insights and Company News

Headcount

6 month growth

-3%

1 year growth

2 year growth

-2%

Yahoo Finance

Oct 19th, 2026

Horizon3, backed by EDBI and SG Growth Capital, opens ASEAN headquarters in Singapore

Horizon3, an AI-native security company, is expanding in Singapore with new investments from EDBI and its parent SG Growth Capital. The amount was not disclosed. The company is setting up its ASEAN headquarters and a Regional Centre of Excellence there, which will also support its growth in Australia and Japan. It will hire locally across sales, customer and partner teams. The move follows Horizon3's $250 million Series E round in August 2026, which valued it at more than $2 billion. Demand is rising as AI-driven attacks grow. Singapore's Cyber Security Agency reported that infected infrastructure in the country rose 142% in 2025 to 284,300 systems.

Business News This Week

Oct 17th, 2026

Horizon3 and Pax8 expand European security partnership.

Horizon3 and Pax8 expand European security partnership. AMSTERDAM, Oct 17 - Horizon3, the AI-Native Proactive Security Company, today announced the expansion of its Pax8 partnership across Europe, bringing the NodeZero(R) Proactive Security Platform to the region's managed service providers (MSPs) through the Pax8 Marketplace. The expansion enables partners to build recurring security services that help small and midsized businesses understand how attackers could compromise their environments, prioritize corrective actions, and verify remediation. Building on the companies' North American marketplace launch, the European expansion makes autonomous offensive security testing accessible to more MSPs and the businesses they protect. Partners can use NodeZero to deliver initial assessments, support remediation engagements, and establish ongoing testing programs without conducting every penetration test manually. Discover more News article writing Weekly business insights Economic growth analysis "MSPs are accountable for protecting their customers' security, but a list of vulnerabilities does not tell them what is actually exploitable, and their level of exposure," said Keith Poyser, General Manager & SVP EMEA, at Horizon3. "NodeZero gives partners that information and a way to fix, and then verify these exploits are remediated. Expanding our relationship with Pax8 brings this capability to more MSPs across Europe, helping them build services around measurable reductions in customer exposure and continuous testing." From Individual Weaknesses to Proven Attack Paths NodeZero autonomously tests production environments using real attack techniques within defined scope and safety controls. Its capabilities span internal and external infrastructure, cloud, and web applications, helping teams understand how exploitable weaknesses can lead to unauthorized access, privilege escalation, and exposure of sensitive data. Rather than treating each finding in isolation, NodeZero chains weaknesses to demonstrate attainable attacker impacts. Results include evidence of successful exploitation, documented attack paths, and prioritized remediation guidance, giving partners a clear basis for recommending what customers should address first. NodeZero WebApp extends this approach to custom, business-critical web applications. It supports authenticated testing to uncover exploitable application weaknesses, including broken access controls and business logic flaws, helping teams assess risks that scanning alone can miss. Business consulting services Building Services Around Measurable Outcomes Multi-tenant support, MSP-friendly licensing, and white-labeled reporting help partners manage testing across customers and incorporate findings into their own service offerings. Partners can build engagements around: * Autonomous penetration testing: Assess customer exposure through repeatable tests across infrastructure, identity, cloud, and web applications. * Prioritized remediation: Direct customer effort toward weaknesses that contribute to demonstrated attacker impacts. * Fix verification: Retest remediated weaknesses to determine whether the previously demonstrated exploitation remains possible. * Threat-focused assessments: Evaluate exposure to supported vulnerabilities in CISA's Known Exploited Vulnerabilities Catalog. * Ongoing security validation: Repeat testing after infrastructure changes, application releases, or control updates to identify new or recurring exposure. This service model gives MSPs a way to maintain an ongoing security conversation with customers. Each engagement can connect a demonstrated risk to a corrective action and a verified result, helping customers understand what their security investment accomplished and where further work is needed. The partnership expansion builds on Horizon3's regional investment, including its EMEA headquarters in Amsterdam, which supports customers, partners, and operations across the region.

Business Wire

Oct 13th, 2026

Horizon3 promotes Keith Poyser to EMEA general manager after 260% revenue growth

Horizon3 has promoted Keith Poyser to general manager for Europe, the Middle East and Africa (EMEA). He was previously vice president, EMEA, and will lead the next phase of the region's growth. The move follows more than 260% regional revenue growth in the last fiscal year and the opening of the security company's EMEA headquarters in Amsterdam. Since Poyser joined in September 2024, the EMEA team has grown from eight to more than 110 employees. "Keith has earned this role," said Snehal Antani, chief executive officer and co-founder of Horizon3. Poyser has more than 20 years of experience scaling technology businesses, including leadership roles at SentinelOne, Palo Alto Networks, and IBM. Horizon3 sells NodeZero, an autonomous security testing tool.

Crypto.com

Sep 15th, 2026

CrowdStrike (CRWD) stock: what's behind Tuesday's premarket dip.

CrowdStrike (CRWD) stock: what's behind Tuesday's premarket dip. News Tue, 15 Sep 2026 13:27:54 UTC 1 hour ago Tldr. * CRWD is down 1.73% to $231.31 in premarket trading Tuesday after a strong sector-wide rally Monday * The pullback is seen as routine profit-taking following a sharp cybersecurity rotation * Monday's rally was sparked by Anthropic CEO Dario Amodei calling for a voluntary slowdown in frontier AI model development * CrowdStrike reported ARR of $5.84 billion in Q2 FY27, up 25% year-over-year * Horizon3 announced a new integration between its NodeZero platform and CrowdStrike Falcon Next-Gen SIEM CrowdStrike (CRWD) pulled back slightly in premarket trading Tuesday, down 1.73% to $231.31, giving back a slice of Monday's gains as investors took some profits after a sector-wide surge. Monday's rally across cybersecurity was triggered by weekend comments from Anthropic CEO Dario Amodei, who called for a voluntary deceleration in frontier AI model development. Sam Altman and Elon Musk also backed the push. Amodei's key concern was that unchecked compute scaling creates serious cybersecurity vulnerabilities. That warning sent capital rotating out of hardware names and into enterprise security platforms. ... Continue reading the full article at the original source below. This content is automatically aggregated. Full credit goes to the original publisher (coincentral.com).

iTWire

Aug 30th, 2026

Horizon3 launches sovereign Sydney instance, bringing the World's Best AI Hacker onshore for Australian organisations.

Horizon3 launches sovereign Sydney instance, bringing the World's Best AI Hacker onshore for Australian organisations. Horizon3 | Published 31 Aug 2026 COMPANY NEWS: New in-country sovereign instance delivers production-safe autonomous security validation with full Australian data residency, enabling government, critical infrastructure, and enterprise customers to continuously prove resilience in the AI vs. AI era. Horizon3, the AI-Native Proactive Security Company behind NodeZero(R), the World's Best AI Hacker(TM), today announced the general availability of its first Asia-Pacific Sovereign Instance, hosted in Sydney. The new Australian point of presence keeps all customer data resident in-country and enables Australian organisations to run continuous, production-safe autonomous penetration testing under full data sovereignty. As adversaries increasingly weaponise AI to discover and exploit vulnerabilities at machine speed, organisations can no longer rely on theoretical findings or periodic assessments. NodeZero continuously validates real, exploitable attack paths across Internal, External, Cloud, Identity, and Web Application surfaces - then drives a disciplined hack-fix-verify loop so customers can prove their defences actually hold. The Sydney Sovereign Instance makes this capability available onshore for the first time in the region, giving Australian organisations a practical way to operationalise Continuous Threat Exposure Management (CTEM) with continuous, attacker-validated evidence. The instance is purpose-built for the highest-trust Australian environments, including government agencies, critical infrastructure operators, Defence Industrial Base organisations, major banks, and other regulated entities. By keeping data resident in Australia and operating under local control, it helps organisations meet key requirements under the SOCI Act, APRA CPS 234, the ASD Essential Eight, and related frameworks, while reducing operational and data sovereignty risk. "Australian organisations face the same AI-accelerated threat landscape as the rest of the world, but they rightly demand that the tools they use to defend themselves meet the highest standards of data residency and national control," said Gareth Cox, Vice President of Sales, Asia Pacific and Japan, Horizon3. "With the Sydney Sovereign Instance, customers can now run the World's Best AI Hacker continuously and safely, knowing their data never leaves Australia. This enables them to move beyond assumptions and continuously prove which exposures actually matter - and that remediation works." "Data sovereignty is no longer a compliance checkbox, it is a strategic requirement for any platform trusted with critical infrastructure and national security workloads," said Snehal Antani, Co-Founder and CEO of Horizon3. "As AI-powered attacks accelerate, countries will only allow continuous, autonomous security validation on their most sensitive networks if they know the data remains under their control and is accessed by cleared nationals. The Sydney Sovereign Instance is the first step in making NodeZero available as a true national-scale capability for Australia." The Sydney instance complements Horizon3's existing points of presence in the United States and Germany and marks the company's first Sovereign Instance in Asia Pacific. It follows Horizon3's recent US$250 million Series E at a valuation exceeding US$2 billion, which is funding accelerated international expansion, including deeper investment across Australia, New Zealand, and the wider Asia-Pacific region. Horizon3's NodeZero platform has already executed more than 310,000 production-safe autonomous security tests for more than 7,500 organisations worldwide, including multinational banks, major healthcare networks, four Fortune 10 enterprises, and national security agencies. The company is FedRAMP High authorised and helps customers meet demanding regulatory regimes globally. With the Sydney Sovereign Instance now generally available, Australian organisations can continuously find, prioritise, and verify the risks that actually matter, while keeping their most sensitive security data under Australian sovereign control.

Horizon3.ai

Senior Technical Support Engineer - Enterprise

About the job