Series A Cybersecurity companies in San Francisco

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

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

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
• 41 employees
• Founded 2020

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

We specialize in Web Application and API penetration Testing, Cyber Threat Intelligence, and Detecting Account Takeovers (ATOs) from attackers. Our DNA is rooted in offensive security, enabling our customers to discover vulnerabilities from an attacker's perspective. We are headquartered in San Francisco, CA.Our products• LeakJarTM, an Early breach detection service, continuously collects and responds to compromised credentials. • Pentoma®, an Automated penetration testing service.• Appsolid®, an Advanced Mobile App Hardening: Protect your Android applications∙Microsoft for Startups∙AWS Technology partner (Public Sector)∙NVIDIA Inception program company∙Cybersecurity 500 company

• Series A
• 32 employees
• Founded 2015