Penetration testing that proves real risk.
AI agents and experienced testers work through your applications, APIs, cloud, and AI systems. A person confirms every finding before it reaches your report, and we retest after you fix it.
No High or Critical finding? No audit fee. Eligible penetration tests only. Read the terms.↗What is Hackstack Security?
Hackstack Security is an independent cybersecurity firm that performs agentic, human-validated penetration testing, AI and LLM security testing, cloud security reviews, and red teaming for product and technology teams worldwide.
AI agents running on local and API-based models extend our coverage and speed. Our testers handle the business logic and attack chains that agents miss, validate every finding, and retest after your team ships a fix.
New York
London
Ahmedabad
The six assessments teams ask for most.
Start with one of these, or browse all 21 services below.
AI & LLM Security
Expert-led security testing for AI-enabled applications, LLM workflows, copilots, agents, retrieval systems, and the APIs that connect them.
AI Red Teaming
Scenario-driven adversarial testing that evaluates how AI systems respond to misuse, manipulation, data exposure, unsafe actions, and control bypass attempts.
Web App Security
Expert-led web application penetration testing that uncovers business logic failures, access control weaknesses, and exploitable risk beyond automated scanning.
API Security
Deep testing for REST, GraphQL, SOAP, and internal APIs, focused on authorization, data exposure, abuse paths, and real-world attacker behavior.
Cloud Security
Architecture and configuration reviews that identify excessive access, exposed services, weak guardrails, and high-impact cloud attack paths.
Red Teaming
Goal-driven attack simulation that tests people, process, and technology against realistic adversary behavior without unnecessary disruption.
How do you use AI agents in penetration testing?
Agents cover ground quickly. Testers go deep where judgment matters. Nothing is reported until a person has reproduced it.
Self-hosted LLM agents
Agents on self-hosted models run inside our isolated testing environment for reconnaissance, attack surface mapping, fuzzing, and hypothesis generation. Your code, traffic, and data stay in that environment.
Frontier models over API
For harder reasoning and exploit chaining we can add frontier models over API. We only do this with your written approval and under the provider’s no-training and retention terms.
Experienced testers
Our testers go after business logic, authorization, multi-step workflows, and chained attack paths. These are the issues that need a tester’s judgment.
No High or Critical finding? No audit fee.
If an eligible penetration test does not uncover at least one validated High or Critical vulnerability, you do not pay the professional fee for that audit.
We put this in writing because agentic coverage plus manual depth is how we find the risk that matters. The guarantee is part of your statement of work before testing starts.
- Eligible tests
Web app, API, mobile, infrastructure, cloud, and AI/LLM penetration tests
- Clear severity
CVSS v3.1 by default: High is 7.0 to 8.9, Critical is 9.0 to 10.0
- Validated only
Reproducible findings with evidence in the final report
- Full access
Agreed scope, access, and test window provided as planned
- Fee waived or refunded
Refund within 30 days if you paid in advance
Penetration testing questions, answered.
The questions buyers ask us most. See all questions or talk to our team.
What is penetration testing?
Penetration testing is an authorized, simulated attack on your applications, APIs, cloud, or infrastructure that finds the vulnerabilities an attacker could actually exploit and proves their impact with evidence. At Hackstack Security every finding is manually validated and delivered with remediation guidance and a retest.
How is a penetration test different from a vulnerability scan?
A vulnerability scan is automated and lists potential weaknesses. A penetration test uses people to confirm which weaknesses are exploitable, chain them into realistic attack paths, and explain the business impact. Scanners support our coverage, but they never replace manual validation.
Do you use AI agents for penetration testing?
Yes. We run AI agents on self-hosted local models and, with your approval, on API-based frontier models to map attack surfaces, fuzz inputs, and generate attack hypotheses. Our testers cover business logic and attack chains manually, and a person validates every agent result before it is reported.
Does our data leave our environment when you use AI models?
Not by default. Local models run inside our isolated testing environment. Third-party model APIs are used only with your prior written approval and under the provider’s no-training and retention terms. We never use client data to train models.
Guides and checklists from our testers.
Practical write-ups on AI security, API testing, cloud reviews, and choosing a testing partner.
How to Security Test MCP Servers in 2026
OAuth audience checks, token passthrough, tool poisoning, SSRF, and the real MCP CVEs.
Testing AI Agents Against the OWASP Agentic Top 10
Each ASI risk turned into test cases you can run before an agent ships.
EU Cyber Resilience Act: The 24-Hour Reporting Rule Is Live
Deadlines, recipients, and a PSIRT readiness checklist for CRA Article 14.
Tell us what you need tested.
Share your targets, deadline, and any compliance driver. We reply with a proposed scope, test approach, and timeline. There is no obligation.