Series A Cybersecurity companies in San Francisco

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

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Ranked by current headcount across Series A Cybersecurity companies in San Francisco. Refreshed daily.

1
Cogent· San Francisco, California, United States
Cogent is an applied AI lab building AI systems for enterprise cybersecurity teams. We focus on cybersecurity because it affects everyone—the reliability of the services we use, the privacy of our data, and the safety of the organizations we depend on. Our mission is to prevent breaches using autonomous AI systems that continuously secure systems against AI-armed adversaries operating at machine speed. Founded by researchers and operators from Google DeepMind, Abnormal Security, and Coinbase. Backed by Greylock Partners.
- Series A
- 92 employees
- Founded 2024
2
Batuta· San Francisco, California, United States
Batuta is orchestrating the future of cybersecurity through Endpoint Intelligence. By intelligently orchestrating every endpoint, the platform eliminates complexity and fragmentation, turning noise into actionable insights. Batuta is a member of the World Economic Forum’s Global Innovators Community and the Centre for Cybersecurity, and is headquartered in San Francisco.
- Series A
- 87 employees
- Founded 2019
3
Reach Security· San Francisco, California, United States
Reach – the AI-Native Security Controls Operating System – integrates with your existing security controls to identify blind spots across your defenses, prioritize fixes, automatically remediate misconfigurations and drift, and activate unused defensive capabilities. It continuously validates that security posture remains strong as your environment and threat landscape evolve.Founded in 2021 during a global pandemic that reshaped how organizations protect their workforce, Reach was built by security veterans from Palo Alto Networks and Proofpoint whose products have been trusted by tens of thousands of organizations. Today, Reach partners with leading security teams and world-class investors to realize a more secure world.
- Series A
- 85 employees
- Founded 2021
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4
Fable Security· San Francisco, California, United States
Fable Security delivers the human risk platform that directly shapes employee behavior. Designed for simplicity and enterprise scale, our agentic platform synthesizes complex employee data, pinpoints risky behaviors, and deploys highly-relevant interventions to people automatically, in real time, right where they work.
- Series A
- 74 employees
- Founded 2024
5
Escape· San Francisco, California, United States
Escape automates the full offensive security lifecycle, multiplying the impact of every security engineer tenfold.Our key products:1. Attack Surface Management: Discover and validate exposure of modern applications, APIs, and infrastructure from code to cloud.2. Business-logic-aware DAST: Replace legacy DAST with business-logic-aware testing that improves over time and helps your team remediate real, exploitable vulnerabilities.3. AI Pentesting: Replace manual pentest and bug bounty programs with a solution that scales. Don’t let your vulnerabilities escape.
- Series A
- 67 employees
- Founded 2020

6
Quantstamp, Inc.· San Francisco, California, United States
Quantstamp is a global leader in blockchain security, on a mission to secure the future of web3. Founded in 2017, the team has honed its expertise through hundreds of audits and worked with some of the top projects in the industry including Maker, Compound, Polygon, Arbitrum, Sandbox, and many more. To date, Quantstamp has performed 750+ audits and secured over $200 billion in digital asset risk from hackers. In addition to providing an array of security services, Quantstamp facilitates the growth and longevity of the web3 space through strategic investments and acting as a trusted advisor to help projects scale. To learn more head to our website Quantstamp.com or follow us on Twitter/X @Quantstamp
- Series A
- 52 employees
- Founded 2017
7
ProjectDiscovery· San Francisco, California, United States
ProjectDiscovery helps security teams detect real, exploitable vulnerabilities without the noise. We combine open source power with enterprise-grade scale, starting with Nuclei, our fast, customizable vulnerability scanner trusted by thousands of engineers. Nuclei delivers attacker-like detections using conditional logic, enabling teams to move beyond version matching and catch what truly matters.Trusted by teams at Elastic, Vercel, and thousands more, ProjectDiscovery brings open-source flexibility to enterprise workflows, enabling full visibility and faster remediation in minutes with zero setup friction.Start with Nuclei. Scale with ProjectDiscovery.
- Series A
- 49 employees
- Founded 2020
8
Monad· San Francisco, California, United States
Monad eliminates the data tax on security operations. We give you the tools to clean, normalize, and route security data exactly how you need it, reducing costs by up to 70% while freeing up your team to actually focus on security.We meet you where you're at—whether you're burning SIEM budget on telemetry, tired of broken pipelines and integrations, or just want to take your SecOps to the next level. We give you the power to make your security data work for you, not against you.
- Series A
- 48 employees
- Founded 2020
9
Mondoo· San Francisco, California, United States
Mondoo's Agentic Managed Vulnerability Service, a combination of local expert security professionals and a proven AI-native platform, delivers the outcomes security professionals need, helping them transition out of the endless cycle of scanning and reporting and into actual remediation. Trusted by more than 300 customers worldwide, including Fortune 50 companies, Mondoo prioritizes risks by business impact and exploitability, collects structured, context-aware data from the entire IT infrastructure, and provides actionable remediation guidance, including automation code and ready-to-approve pull requests, that eliminates vulnerabilities rather than just categorizing them.Mondoo's customers have reduced vulnerabilities by 60%, achieved mean-time-to-remediation under 16 days, and accelerated remediation 10x faster than manual approaches. With seamless ITSM integrations, transparent security pipelines, and guaranteed outcomes, Mondoo bridges the gap between security and engineering to fix what matters most to the business
- Series A
- 42 employees
- Founded 2020
10
RAD Security· San Francisco, California, United States
RAD Security is the creator of Agentkeeper, an AI Governance Platform allowing you to secure autonomous agents. Rad is your AI security core.
- Series A
- 37 employees
- Founded 2021

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Find engineers at Series A Cybersecurity companies in San Francisco

Searching for “engineers at top Series A Cybersecurity companies in San Francisco” surfaces this slice of the market. The list above ranks Cybersecurity companies headquartered in San Francisco whose latest disclosed round is Series A, by current headcount, drawn from public LinkedIn and Crunchbase records. With 22 matching companies in Refolk’s index, this is a tight read on where the Cybersecurity talent in San Francisco is heating up.

Three filters at once narrows the field hard. The companies that survive all three - Series A, Cybersecurity, in San Francisco - are usually the most targeted recruiting pool a hiring manager can ask for. Senior engineers, founding designers, and product leads here are about to become Cybersecurity’s next operators and angel investors.

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How this list is built

Refolk pulled Cybersecurity companies headquartered in San Francisco whose latest disclosed funding round is Series A from public LinkedIn and Crunchbase records, ranked them by current employee count, and kept those with at least 3 employees. The list refreshes once a day.

Last refreshed: Wed, 05 Aug 2026 12:39:50 GMT

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