Top Cybersecurity companies in San Francisco

Companies defending or attacking software, networks, and cloud infrastructure. Filtered to companies headquartered in San Francisco.

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Ranked by current headcount across Cybersecurity companies headquartered in San Francisco. Refreshed monthly.

1
Cloudflare· San Francisco, California, United States
Cloudflare, Inc. (NYSE: NET) is the leading connectivity cloud company. It empowers organizations to make their employees, applications and networks faster and more secure everywhere, while reducing complexity and cost. Cloudflare’s connectivity cloud delivers the most full-featured, unified platform of cloud-native products and developer tools, so any organization can gain the control they need to work, develop, and accelerate their business. Powered by one of the world’s largest and most interconnected networks, Cloudflare blocks billions of threats online for its customers every day. It is trusted by millions of organizations – from the largest brands to entrepreneurs and small businesses to nonprofits, humanitarian groups, and governments across the globe.
- Post-IPO debt
- 8.2k employees
- Founded 2009
2
Okta· San Francisco, California, United States
Okta, Inc. is The World’s Identity CompanyTM. We secure identity, so everyone is free to safely use any technology. Our customer and workforce solutions empower businesses and developers to use the power of Identity to drive security, efficiencies, and success — all while protecting their users, employees, and partners. Learn why the world’s leading brands trust Okta.
- Post-IPO equity
- 7.9k employees
- Founded 2009
3
HackerOne· San Francisco, California, United States
HackerOne is a global leader in Continuous Threat Exposure Management (CTEM) and the only solution provider that pairs the simultaneous trust of the Fortune 500 and the world's largest community of security researchers to secure the AI-native enterprise. The H1 Platform unites agentic AI solutions with security researchers ingenuity to continuously discover, validate, prioritize, and remediate exposures across code, cloud, and AI systems. Through solutions like bug bounty, vulnerability disclosure, agentic pentesting, AI red teaming, and code security, HackerOne delivers measurable, continuous reduction of cyber risk for enterprises. Industry leaders, including Anthropic, Crypto.com, General Motors, Goldman Sachs, Lufthansa, Uber, UK Ministry of Defence, and the U.S. Department of Defense, trust HackerOne to safeguard their digital ecosystems. HackerOne was recognized in Gartner’s Emerging Tech Impact Radar: AI Cybersecurity Ecosystem report for its leadership in AI Security Testing.
- Series unknown
- 7.2k employees
- Founded 2012
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4
Bugcrowd· San Francisco, California, United States
We are a crowdsourced security company that safeguards organizations' assets from sophisticated threat actors before they can strike—by uniting our customers with trusted hackers via our AI-powered platform to take back control and stay ahead of attackers. Bugcrowd is backed by Blackbird Ventures, Costanoa Ventures, Industry Ventures, Paladin Capital Group, Rally Ventures, Salesforce Ventures and Triangle Peak Partners.
- Debt
- 3.9k employees
- Founded 2012
5
Armis· San Francisco, California, United States
Armis, the cyber exposure management & security company, protects theentire attack surface and manages an organization’s cyber risk exposure inreal time.In a rapidly evolving, perimeter-less world, Armis ensures that organizations continuously see, protect and manage all critical assets - from the ground to the cloud. Armis secures Fortune 100, 200 and 500 companies as well as national governments, state and local entities to help keep critical infrastructure, economies and society stay safe and secure 24/7. Armis is now part of ServiceNow. Learn more at servicenow.com.
- Series unknown
- 918 employees
- Founded 2015

6
Cobalt· San Francisco, California, United States
Cobalt is a leader in continuous offensive security. Only Cobalt brings together human expertise, a context aware platform, AI-driven orchestration, and the industry's largest dataset of real-world pentest results. Thousands of customers rely on Cobalt and its global network of 500+ security experts to continuously identify, prioritize, and remediate risk.
- Series B
- 597 employees
- Founded 2013
7
Horizon3.ai· San Francisco, California, United States
Horizon3.ai answers the two most important questions in cybersecurity: If someone tried to compromise us, would we hold up? And, how do we withstand the onslaught of AI-powered attacks?Horizon3.ai’s NodeZero® shifts the advantage from attackers to defenders by giving organizations the power to fight AI with AI. The Proactive Security Platform autonomously tests your defenses at machine speed, safely finds and prioritizes exploitable attack paths, instantly verifies fixes, and drives a continuous loop so you can prove you’re resilient, not just hope you are.NodeZero, the World’s Best AI HackerTM, was built by an elite team of U.S. cyber veterans and has honed its skills over 225K production-safe tests, more than all manual pentests in history. More than 5,000 organizations including the NSA, CISA, Fortune 100 giants, and major healthcare providers trust Horizon3.ai to prioritize what matters and prove they’re ready for what’s next.Horizon3.ai has been recognized by Fast Company as one of the World’s Most Innovative Companies in 2026. The company ranked #3 overall on the 2025 Deloitte Technology Fast 500 and was named the #1 cybersecurity company on the Inc. 5000 in 2025. It has also been named to the Fortune Cyber 60 in both 2023 and 2025 and is a two-time Black Unicorn Award winner.
- Series E
- 579 employees
- Founded 2019
8
Sysdig· San Francisco, California, United States
Good-enough security isn’t good enough.Sysdig helps security and development teams prevent, detect, and respond to cloud threats instantly. Founded by Falco and Wireshark creators and built on agentic AI, Sysdig delivers real-time defense grounded in the uncompromising truth of runtime. With streaming views of what’s running, Sysdig correlates signals across workloads, identities, and services to expose hidden attack paths and active risk, enabling teams to tailor defenses together. No guesswork. No black boxes. Just cloud security, the right way.
- Series G
- 562 employees
- Founded 2013
9
Upwind Security· San Francisco, California, United States
Upwind Cloud Security Platform bridges intelligence from runtime to build-time, eliminating friction & boosting the productivity of your developers, security engineers, and DevOps.Upwind delivers comprehensive cloud security, precisely when and where it’s most critical.
- Private equity
- 539 employees
- Founded 2022
10
Corelight· San Francisco, California, United States
Corelight transforms network data into definitive evidence, powering AI-driven detection and expert-authored workflows, and enabling the AI SOC ecosystem.Delivered by our open NDR platform, Corelight’s comprehensive, correlated evidence gives you unparalleled visibility into your network. This evidence allows you to unlock new analytics, investigate faster, hunt like an expert, and even disrupt future attacks.Our on-prem and cloud sensors go anywhere to capture structured, industry-standard telemetry and insights that work with the tools and processes you already use. Corelight’s global customers include Fortune 500 companies, major government agencies, and research universities.Get started >> https://www.corelight.com/contact
- Series E
- 483 employees
- Founded 2016

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Find engineers at Cybersecurity companies in San Francisco

San Francisco has long been a hub for Cybersecurity, and the list above ranks the largest Cybersecurity companies headquartered there by current headcount, drawn from public LinkedIn and Crunchbase records. With 140 matching companies in Refolk’s index, this is a good map of where the Cybersecurity talent in San Francisco lives - useful whether you’re recruiting, partnering, or sizing a market.

The biggest Cybersecurity companies in San Francisco tend to be the gravitational centres for specialised talent - senior engineers, ML researchers, applied scientists, designers - while the smaller ones compete on speed, equity, and proximity to founders.

Refolk converts this list into a live search. Ask for “Cybersecurity engineers in San Francisco hiring senior staff” or “founders of Cybersecurity companies in San Francisco who left in the last 12 months” and Refolk returns a ranked shortlist with the evidence that earned each person a spot.

How this list is built

Refolk pulled Cybersecurity companies headquartered in San Francisco from public LinkedIn and Crunchbase records, ranked them by current employee count, and kept those with at least 10 employees. The list refreshes monthly.

Last refreshed: Fri, 18 Sep 2026 07:49:10 GMT

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The list draws on the public company graph - headcount and growth signals, funding history, and recency. The criteria chips at the top show exactly which filters produced it, and the methodology section explains the ranking.

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