See Your Risks.Secure Them Faster.
We provide a clear picture of your cyber risks - across IT, OT, and your entire supply chain - so you can act before attackers do.
Is your domain being spoofed?
Free · No login · Results in seconds
What We Offer
Services and Products in one place.
IT Penetration
Testing
Networks, apps, cloud & APIs
OT Penetration
Testing
ICS & SCADA environments
Industrial
Cybersecurity
End-to-end OT protection
Due
Diligence
Pre-acquisition cyber risk
CISO
as a Service
Fractional security leadership
Private Equity
Portfolio Monitoring
Continuous portfolio risk visibility
IT Penetration Testing
We simulate real-world attacks across your web apps, internal network, cloud, and APIs to find exploitable gaps before attackers do — then give you a prioritized fix list your team can act on immediately.
Trusted. Tested. Different.
Proven cybersecurity expertise with real-world results.
Built by Cybersecurity Operators
→Hands-on experts with offensive and defensive field experience—not just theorists.
Unified IT & OT Coverage
→End-to-end visibility across enterprise networks and industrial systems.
Real-Time Portfolio Monitoring
→Track evolving risks across companies and suppliers instantly.
Clarity-First Reporting
→Actionable, easy-to-understand reports for leadership and technical teams.
Recognition
Awards & Certifications
Cyber Essentials Certified
Top Pentest Provider 2025
Cyber Security Review
OpenAI Certified
Testimonials
“In the medical device space, understanding emerging threats and supply chain risk is essential. Atumcell's threat intelligence keeps us informed, and their supply chain assessment gives us confidence in our vendor ecosystem. The portfolio dashboard ties everything together and provides clear visibility at the board level.”
Mike T., Chairman
Medical device developer
“We advise private equity firms on M&A transactions, and cybersecurity due diligence is a critical piece of that process. Atumcell works alongside our IT diligence team seamlessly. Their assessments are fast, thorough, and give our clients the clarity they need to make informed investment decisions.”
David L., Partner
Private equity M&A consultant
“Atumcell brings deep expertise in both IT and OT security, which is rare. They know how to test and monitor sensitive OT environments safely, something IT-only firms simply can't do. That capability has been critical for protecting our pipeline operations.”
Chris S., President and CFO
Midstream pipeline
About Atumcell
The team and vision behind Atumcell.
Our Mission
Atumcell exists to deliver clarity in cybersecurity — enabling businesses, investors, and industries to grow with confidence.
Our Difference
Atumcell brings expertise across IT, OT, and industrial systems, offering real-time visibility through proprietary tools like AtumScan and AtumScreen. Services are strategically tailored for C-suites, investors, and operators, with a firm commitment to responsible testing and actionable results.
About
Atumcell is a cybersecurity firm built for a world where IT, OT, and cloud converge. We combine deep technical expertise with real-world offensive security experience to uncover hidden risks before attackers do. Our team has been recognized for excellence in penetration testing, industrial cybersecurity, and threat intelligence.
Ready to talk? Drop us an email or book a demo — we'll respond the same business day.
Founders & Advisors
Building Trust and Resilience in a Connected World
David Williams
Co-Founder | CEO
David brings decades of experience across healthcare technology, policy, and risk — working with The Boston Consulting Group and MedPharma Partners across North America, Europe, and Asia. He now focuses on using software to reduce drudgery and protect people from harm.
Matthew Carr
Co-Founder | Head of Research & Technology
Matthew is an award-winning cybersecurity researcher and penetration tester with senior roles at IKEA, IBM, and SecureLink. His research has been featured by the BBC, The Register, and Fox News — including two Zero-Day discoveries, one with national-security impact.
Mikael Totterman
Entrepreneur, technology executive, investor
Trevor McCaw
Technology entrepreneur, commercialization expert
Christy Alvord
Industrial executive, board member
Insight
Stay ahead with the latest publications, research briefs, and expert perspectives on cybersecurity.
Web App Penetration Testing
Driving Portfolio-wide Value with Cybersecurity
Atumcell Publications
Explore our latest whitepapers, case studies, and reports designed to strengthen security strategy.
Frequently Asked Questions About Atumcell
Atumcell is a cybersecurity firm specializing in penetration testing, OT/ICS security, private equity portfolio monitoring, and CISO advisory services. We help organizations identify and fix security vulnerabilities before attackers do — through hands-on technical assessments, continuous monitoring tools, and executive-level security leadership.
Atumcell works with mid-market and enterprise organizations across manufacturing, healthcare, energy, financial services, and B2B SaaS. Our typical clients include CISOs, CIOs, CTOs, and private equity firms managing cyber risk across portfolio companies.
Atumcell is a boutique firm — every engagement is led by senior practitioners, not junior analysts following a script. We combine offensive security expertise (penetration testing, red teaming) with strategic advisory (fractional CISO, GRC) and purpose-built SaaS tools (AtumScan, SpoofCheck). We're vendor-neutral and do not resell software.
SpoofCheck is a free email security scanner that checks whether your domain can be spoofed — analyzing your SPF, DMARC, and MX records in seconds. No account required. It's the most-used free tool we offer and is available at atumcell.com/tools/spoofcheck.
Yes. Atumcell has deep expertise in industrial cybersecurity — including OT penetration testing, IEC 62443 gap assessments, and non-disruptive assessments of SCADA, PLC, and historian systems. We have delivered OT security engagements for energy, manufacturing, and midstream pipeline operators.
The fastest way is to book a free 30-minute scoping call at calendly.com/atumcellceo/30min. You can also use our free SpoofCheck tool to get an instant read on your email security posture, or contact us directly at contact@atumcell.com.
Built for security teams.
No login required.
Used by 120+ security teams · Results in seconds · No credit card
CIS 18 Controls Self-Assessment
Find out how well your organization covers the CIS 18 Critical Security Controls — the baseline cyber insurers, investors, and regulators now expect. 18 questions, instant gap report.
Sample gap report
Vendor Cybersecurity Questionnaire
Assess the cyber risk of any vendor or supplier in minutes. 20 questions covering security policy, access controls, incident response, compliance, and data handling.
Sample output
Discover Your
Cyber Risk Level.
Find out in seconds if your domain can be spoofed. Free, no login required.
Fixed-scope pricing agreed before we start · Actionable insights · No commitment required
