Get to Know Us

Horizon3 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.

We are seeking a hands-on Senior OR Staff Site Reliability Engineer to own and evolve the reliability strategy, operating model, and engineering-wide standards supporting our platform. This is a foundational role for an experienced engineer who will set technical direction across teams, lead the highest-impact reliability initiatives, and establish the practices and systems that enable engineering to operate production services safely.

What You’ll Do

Own and evolve the engineering-wide SRE strategy, operating model, and reliability standards, aligning them to customer impact, business priorities, and risk.
Lead cross-functional alignment across Infrastructure, product, service, security, and business stakeholders to improve reliability, observability, incident response, and operational readiness across multiple teams.
Establish an organization-wide approach to service ownership, meaningful SLIs and SLOs, and error budgets for critical customer paths and services.
Define and drive adoption of observability standards across pipelines and platform components that report on service health, performance and operational risk.
Set the standard for dashboards, actionable alerting, runbooks, and escalation paths.
Drive end to end complex cross-functional reliability initiatives.
Set and raise the engineering wide bar for incident management, incident command, on-call health, post-incident learning, and recovery readiness.
Shape the technical direction, operationable model, and growth path of the SRE function.
Participate in a 24/7 on-call rotation and help design an on-call model that is sustainable, appropriately staffed, and continuously improved.

What You’ll Bring

Experience designing, operating, and troubleshooting large scale distributed systems in production environments.
Deep knowledge of reliability engineering, observability, incident management, and production operations, with demonstrated ability to turn that knowledge into standards and practices adopted by others
Experience in establishing SLIs, SLOs, actionable alerts, observability, and service ownership.
Backend experience building backend systems and automation that reduce optional toil, strengthen safeguards, and operational efficiency.
Experience in leading high severity incidents and improving incident response programs.
Excellent written and verbal communication skills including technical designs, runbooks, postmortems, and operational documentation.

Required Tech Stack Experience

Python and Terraform (Infrastructure as Code), or equivalent automation and infrastructure-as-code tools.
Experience with Observability tools such as Datadog, New Relic, Grafana, or equivalent platforms.
Experience operating production services in AWS and Kubernetes
Experience with CI/CD pipelines such as Gitlab CI, ArgoCD, or GitOps workflows..

Travel Required

We are a fully remote company, and this job may require up to 10% of travel to be successful. Travel primarily consists of team off-sites and in-person project kick-offs.

Perks of Horizon3

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.
Hybrid & Remote Work: We embrace a mix of remote and hybrid work models depending on role and location, including our Chicago office, where some roles require regular in-office presence.
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.

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.

In accordance with various State’s transparency regulations, we provide the following salary range information for this position:

Base salary range: $199,750 - $270,000 annually. The exact salary will be determined based on the selected candidate’s location, qualifications, experience, and relevant skills.
Additional compensation: All full-time roles are eligible for an equity package in the form of stock options.

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, 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

Get referred to Horizon3.ai

See people who can refer or advise you

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/Staff Site Reliability Engineer

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