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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Built from a search like: “Top Series A Cybersecurity companies in San Francisco”

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

1
Cogent· San Francisco, California, United States
Cogent is an applied AI lab building AI systems for enterprise cybersecurity teams. 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
- 107 employees
- Founded 2024
2
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
- 92 employees
- Founded 2021
3
Batuta· San Francisco, California, United States
Batuta is a cybersecurity software and managed services company.Through Batuta Platform, our AI-powered platform used by both customers and our security analysts, we help organizations continuously reduce cyber risk with fast, scalable security operations.
- Series A
- 82 employees
- Founded 2019
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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
- 82 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
- 76 employees
- Founded 2020

6
Kai· San Francisco, California, United States
Kai is the AI company rebuilding cybersecurity for the machine-speed era. Founded by the creators of category-defining companies Claroty and SecurityMatters, and trusted by Fortune 500 enterprises, Kai is building a future where security has no categories, no silos, and no human-speed bottlenecks. The Kai Agentic AI Platform replaces fragmented, human-limited workflows with agentic AI systems that continuously contextualize, assess, reason, and execute security work at machine speed - making human defenders, superhuman.
- Series A
- 68 employees
- Founded 2024
7
Neeve· San Francisco, California, United States
Neeve is a cloud PaaS company transforming smart buildings, spaces and critical infrastructure, making them simpler, smarter, and more secure. As a trusted partner to owners, occupiers, operators, and integrators, our edge and cloud technology is securing operational technology (OT) and enabling the AI transformation of OT operations around the world. We are committed to being human, keeping it simple and always improving.
- Series A
- 58 employees
- Founded 2024
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
- 54 employees
- Founded 2020
9
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
- 51 employees
- Founded 2017
10
ProjectDiscovery· San Francisco, California, United States
Software ships daily. Security testing happens quarterly, or once a year. Everything in between goes untested, and the gap widens as AI agents write a growing share of the code.From the founders of popular open source tools like Nuclei, httpx, subfinder and more, Neo is ProjectDiscovery's unified offensive testing and regression platform for vulnerability management. One engine pentests code, web apps, APIs, networks, and cloud on every PR and release, validates what is exploitable, and enforces every fix as a permanent regression test.In a head-to-head benchmark against DAST scanners and AI security tools, Neo found 24 exploitable vulnerabilities no other tool caught, with the lowest false positive rate of anything tested. Security compounds release over release.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 Neo.
- Series A
- 50 employees
- Founded 2020

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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 27 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 monthly.

Last refreshed: Fri, 18 Sep 2026 07:50:09 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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