Top Penetration Testing Companies In San Francisco For 2027

San Francisco companies ship software fast. A SaaS startup may deploy dozens of times a day, connect a large language model to its customer data in a single sprint and add a new cloud service before anyone has reviewed the permissions. Every change is a chance for a flaw to slip into production, and attackers are using AI to find those flaws faster than before. Automated tools now scan for exposed APIs, chain weak settings into full compromises and test stolen credentials at a scale that used to take a team of people.

A good penetration test tells you what a skilled attacker could actually do with the weaknesses in your applications, cloud accounts and AI features, and in what order you should fix them. The Bay Area has an unusual mix of providers to choose from: research-driven boutiques that read your source code line by line, crowdsourced and pentest as a service platforms that can start a test within days, and newer firms using AI agents to run continuous attacks.

This list covers ten penetration testing companies headquartered in the San Francisco Bay Area or with a staffed San Francisco office. For a national view, see our list of top penetration testing companies, and if you are still deciding what kind of test you need, our guide to PTaaS vs traditional penetration testing explains the trade-offs.

Penetration Testing Companies In San Francisco At A Glance

Company	Headquarters	Best For	Core Services
Bishop Fox	Tempe, AZ, USA (San Francisco office)	Enterprises that want expert-led testing plus continuous coverage	Application, cloud, network and hardware pentests, red teaming, AI and LLM assessments, Cosmos platform
Doyensec	San Francisco, CA, USA	Engineering-led companies that want a deep manual application review	Web, API, mobile, desktop and Electron testing, GraphQL, cloud, reverse engineering, LLM security
RunSybil	San Francisco, CA, USA	Fast-shipping AI and SaaS teams that want testing on every deployment	Autonomous penetration testing, continuous security testing, exposure validation, SOC 2 pentests
HackerOne	San Francisco, CA, USA	Companies with a public product that want researcher coverage at scale	Agentic pentest, bug bounty, AI red teaming, vulnerability disclosure
Bugcrowd	San Francisco, CA, USA	Growth-stage and enterprise teams that want several testing models from one vendor	Pen test as a service, specialized AI and cloud pentests, red team as a service, bug bounty
Horizon3.ai	San Francisco, CA, USA	IT and security teams that need frequent internal and cloud tests	NodeZero autonomous pentesting for internal, external, cloud, Kubernetes and Active Directory
Synack	Redwood City, CA, USA	Enterprises and government agencies that want a vetted tester pool	PTaaS, Synack Red Team, Sara AI pentesting agent, attack surface management
Kroll	New York, NY, USA (San Francisco office)	Regulated firms that want testing tied to incident response	Network, web app, API, mobile and cloud pentests, red teaming, IoT testing, incident response
Baker Tilly	Chicago, IL, USA (San Francisco offices)	Companies that want pentests bundled with SOC 2 and compliance work	Penetration testing assessment, vulnerability assessment, SOC 2 reporting, PCI DSS, HIPAA, FedRAMP
Parameter	San Francisco, CA, USA	Early-stage startups that need continuous testing and compliance evidence	Autonomous pentesting agent, pull request review, cloud misconfiguration checks, secrets detection

Best Penetration Testing Companies In San Francisco For 2027

1. Bishop Fox — Expert Pentesting Plus The Cosmos Continuous Testing Platform

Bishop Fox is an offensive security firm with its global headquarters in Tempe, Arizona, and a San Francisco office at 2107 Union Street. Its consulting practice covers application penetration testing, including mobile apps and secure code review, along with cloud testing for AWS, Azure and Google Cloud, internal and external network tests, hardware and device security, and AI and LLM security assessments that look at models and the architecture around them.

The firm also runs Cosmos, a continuous offensive security platform that combines attack surface discovery with ongoing testing and emerging threat checks, so clients are not left exposed between annual engagements. Its red team service emulates real attackers across technical, physical and social routes, and it offers ransomware readiness work and incident response tabletop exercises. Bishop Fox is a good fit for mid-size and large companies that want one partner for deep manual testing and always-on external coverage. Smaller teams with a single web app may find a narrower provider more cost effective.

2. Doyensec — Research-Driven Application Security From A Townsend Street Office

Doyensec is a specialist application security testing consultancy with its US office at 350 Townsend Street in San Francisco and a European office in San Marino. Its work focuses on software rather than networks: web applications and APIs, mobile apps, desktop and server software, GraphQL platforms, ElectronJS applications, smart contracts and IoT devices. It also handles cloud security reviews, reverse engineering and security automation for clients that want tooling built into their pipelines.

Doyensec tests large language model applications as well, which suits AI startups that have wired models into their products and need someone to look hard at prompt injection, data exposure between users and unsafe tool use. The firm publishes research and a technical blog, which gives buyers a sense of how its testers think before signing. It is best for product companies that can share source code and want a focused, high-skill engagement on a specific product, rather than organizations that need broad, frequent scans across hundreds of assets.

3. RunSybil — AI Agent Pentesting Built By OpenAI And Meta Security Veterans

RunSybil builds Sybil, an AI agent that runs continuous penetration tests against live applications and infrastructure. Instead of matching signatures, Sybil maps code, APIs, cloud and infrastructure, reasons like an attacker and chains weaknesses into exploitable attack paths. It updates its view of the attack surface with each deployment, can flag issues at the pull request stage, and is positioned to validate whether findings from other tools are actually exploitable.

The company was co-founded in 2023 by Ari Herbert-Voss, who was OpenAI’s first security research hire, and Vlad Ionescu, who previously led offensive security red teams at Meta. In 2026 it raised $40 million in a round led by Khosla Ventures, and it names Cursor, Notion and Baseten among its customers. RunSybil suits AI-native companies that deploy many times a day and want autonomous pentesting that keeps pace. It also offers SOC 2 penetration testing, though buyers with complex business logic should still budget for periodic human review.

4. HackerOne — Agentic Pentests Backed By A Global Researcher Community

HackerOne is headquartered in San Francisco and connects organizations with a global community of security researchers. For structured testing it offers H1 Agentic Pentest, which pairs AI agents with human experts so coverage can grow with the attack surface. Alongside that it runs H1 Bounty programs for continuous hunting, time-boxed H1 Bounty Challenges for a specific scope, and vulnerability disclosure programs for receiving reports from outside researchers.

Its AI red teaming service tests AI systems and models and maps the results to the OWASP LLM Top 10, MITRE ATLAS and the NIST AI Risk Management Framework, which gives security and compliance teams a shared language for findings. HackerOne is a good fit for companies that already have a mature intake process and enough engineering capacity to fix a steady flow of reports. Teams that need a single, scoped report for an audit may prefer a classic engagement, which HackerOne can also deliver through its pentest product.

5. Bugcrowd — Pen Test As A Service Plus Red Team And Bug Bounty

Bugcrowd runs a crowdsourced security platform and lists headquarters in San Francisco. Its Pen Test as a Service offering uses external attack surface data to shape each engagement, and it runs specialized tests for AI systems, web and mobile applications, networks, APIs, IoT devices and cloud environments. The same platform manages bug bounty programs, vulnerability disclosure and attack surface management.

Bugcrowd also offers Red Team as a Service for objective-based attacks that test people and processes, not just systems, and it is building Savant Pathseeker, an agentic pentesting product that was in early access at the time of writing. The appeal is flexibility: a company can run a scheduled pentest for a compliance audit, keep a bug bounty open between tests and add a red team exercise once its defenses mature. It suits buyers comfortable working with external testers through a platform rather than a single consulting team.

6. Horizon3.ai — NodeZero Autonomous Pentests For Networks, Cloud And AD

Horizon3.ai is headquartered in San Francisco and builds NodeZero, an autonomous pentesting platform. NodeZero runs internal, external, Kubernetes, cloud and Active Directory tests, plus web application testing, without a human operator driving each step. It looks for the same things an attacker would after gaining a foothold, such as weak credentials, misconfigurations and paths to sensitive data, and then shows how they chain together.

The main advantage is frequency. A traditional internal test happens once or twice a year, while NodeZero can run whenever infrastructure changes so teams can confirm that fixes worked. The platform also covers PCI and NIS 2 compliance testing, security control validation and rapid response checks for newly exploited vulnerabilities on the CISA KEV list. Horizon3.ai fits mid-size and large organizations with complex internal networks. It complements rather than replaces human testers for business logic flaws, and our list of automated penetration testing platforms compares it with similar tools.

7. Synack — Vetted Synack Red Team Paired With The Sara AI Agent

Synack has its headquarters in Redwood City, on the Peninsula south of San Francisco. Its penetration testing as a service platform combines human and AI testing across web applications, hosts, cloud, APIs and mobile apps, with reporting, vulnerability management and integrations built in. The human side is the Synack Red Team, a network of more than 1,500 vetted security researchers who look for logic flaws and chained exploits that scanners miss.

Synack’s newer addition is Sara, an agentic AI pentesting system that identifies, validates and prioritizes vulnerabilities across the attack surface alongside human testers. The combination helps large organizations test more often without giving up expert judgment, and the vetting model appeals to buyers who are uneasy about opening their systems to an open crowd. Synack fits enterprises and public sector agencies that want continuous testing under one contract. Small startups may find a single scoped engagement simpler to buy.

8. Kroll — Penetration Testing Backed By A Frontline Incident Response Team

Kroll is a New York-headquartered risk advisory firm with a San Francisco office at 550 California Street. Its cyber practice runs external and internal network penetration tests, web application, API and mobile app tests, cloud penetration testing, container security reviews and IoT and hardware device testing. It also offers application threat modeling and an agile penetration testing program that builds testing into the software development lifecycle.

What sets Kroll apart is the link to incident response. Its testers work alongside a large digital forensics and response team, so findings are shaped by what real attackers have done in recent breaches, and red team engagements test how people, processes and technology hold up against ransomware and social engineering. Kroll suits financial services, healthcare and professional services firms that want one provider for proactive testing and crisis support. Its findings come with the context of what attackers are doing right now.

9. Baker Tilly — Penetration Testing Alongside SOC 2, PCI And HIPAA Assessments

Baker Tilly is an advisory and accounting firm headquartered in Chicago with two San Francisco offices, at 333 Bush Street and 50 Fremont Street. Its cybersecurity group runs penetration testing assessments and vulnerability assessments as part of a wider set of services that includes SOC 1, SOC 2 and SOC 3 reporting, PCI DSS assessments, HIPAA and HITRUST work, and federal assessments such as CMMC and FedRAMP.

That mix is useful for SaaS and fintech companies whose main reason for testing is an audit or a customer security review. Running the pentest and the compliance work with one firm can reduce the back and forth over evidence and scope. Baker Tilly also offers AI governance advisory, third-party vendor risk management and incident response planning. It is less suited to buyers who want deep exploit research or red team operations, which its service list does not cover, but it is a practical choice for compliance-driven testing.

10. Parameter — Autonomous Pentesting Agent With Proof Of Concept For Each Finding

Parameter is a San Francisco startup, formerly known as Hex Security and backed by Y Combinator, that runs continuous AI penetration tests across code, cloud and dependencies. Customers provide a URL and credentials, and the company says first findings arrive within 24 hours. Each finding comes with a proof of concept, and the agents stop after proving a vulnerability rather than chaining or escalating attacks without explicit approval, which addresses a common worry about autonomous testing in production.

Beyond the pentesting agent, Parameter includes Sentinel, an AI reviewer that checks pull requests before they merge, along with cloud misconfiguration checks, supply chain alerts for vulnerable packages, external asset monitoring and secrets detection. It publishes framework pages for SOC 2, ISO 27001, PCI DSS and HIPAA evidence. Parameter is a young company, so it best suits startups that want broad, automated coverage at a low operating cost. Larger enterprises will want to pair it with a human-led test for complex systems.

How To Choose A Penetration Testing Company In San Francisco

Bay Area buyers can pick from boutiques, platforms and AI-driven tools, and they are not interchangeable. These questions help match the provider to the job.

Do I Need A Boutique, A Platform Or An AI Tool?

Boutiques that focus on application security testing are best when the target is complex or high stakes, such as a core product, a cryptographic design or an AI feature that touches customer data. Pentest as a service and crowdsourced platforms suit teams that need frequent tests across many apps on a predictable schedule. Autonomous pentesting tools are good at broad, repeated coverage of networks and common web flaws, but they do not replace a human reviewing business logic. Many SaaS companies use one of each over a year.

Will The Testers Look At Source Code?

A black-box test only sees what an outside attacker sees. If you can share code, a white-box or source-assisted test usually finds more serious issues in less time, especially in authentication, authorization and multi-tenant logic. Ask each provider how it works with code, what access it needs and how it handles your intellectual property.

Can They Test Our AI Features And Agents?

If your product uses large language models, ask whether the provider tests for prompt injection, data leakage between tenants, unsafe tool use by agents and abuse of model APIs. Ask for an example finding from a past AI engagement, with client details removed. For dedicated AI testing, see our list of AI red teaming companies.

Will The Report Satisfy Our Auditors And Customers?

Enterprise buyers and SOC 2 auditors often ask for a recent third-party test. Confirm that the report includes scope, methodology, severity ratings and evidence, and that the provider will retest fixes and issue a letter of attestation you can share with customers.

How Is Pricing Structured?

Boutiques usually price by the number of tester days a scope requires. Platforms often sell credits or annual subscriptions, while bug bounty programs pay per valid finding on top of a platform fee. Ask for a written scope and estimate before you commit, and check what retesting costs.

Conclusion

San Francisco offers some of the deepest penetration testing talent in the country, alongside the platforms and AI tools that many SaaS companies now rely on for ongoing coverage. Decide first whether your biggest risk is a single critical system that needs expert eyes or a large, fast-changing estate that needs frequent testing, then choose the provider whose model fits that need. Whichever you pick, ask for a retest so the report ends with fixed issues, not just a list of findings.