APIs expose your core business logic directly to clients — and to attackers. Our API penetration testing maps every endpoint, parameter and object relationship, then attacks authorization, input handling and rate controls against the OWASP API Security Top 10.
We test the API the way integrations actually use it, uncovering broken object-level authorization (BOLA), mass assignment and token flaws that automated tools consistently miss.
We test REST, GraphQL, gRPC and WebSocket APIs against the OWASP API Security Top 10, working directly from your OpenAPI/Swagger specification, Postman collection or captured traffic. Our API penetration testing maps every endpoint, parameter and object relationship, then attacks authorization at the object and function level, token and JWT handling, mass assignment and rate limiting. For microservice and B2B APIs, we pay particular attention to the trust boundaries between services where broken authorization so often hides.
API Penetration Testing: manual, exploit-led coverage — web, API, cloud, network and AI-agent security.
Why it matters
APIs now carry the majority of application traffic and expose core business logic directly to clients and partners — which is why the OWASP API Security Top 10 exists as its own standard. Broken object-level authorization (BOLA) alone is behind a large share of major data breaches.
Because APIs are consumed by machines, not browsers, client-side controls provide no protection: only server-side authorization and validation matter, and that is exactly what dedicated API penetration testing verifies.
What we test
Broken object-level authorization (BOLA)
Broken function-level authorization (BFLA)
Mass assignment & excessive data exposure
Authentication & JWT/token weaknesses
Rate-limiting and resource-exhaustion bypass
Injection and server-side request forgery
Common vulnerabilities we uncover
Broken object-level authorization (BOLA)
Broken function-level authorization (BFLA)
Mass assignment and excessive data exposure
JWT and token authentication weaknesses
Rate-limiting and resource-exhaustion bypass
Injection and server-side request forgery (SSRF)
Our methodology
Scoping & rules of engagement. We agree objectives, targets and boundaries for your api penetration testing, so testing is safe, authorized and focused on what matters to your business.
Reconnaissance & mapping. We enumerate the full attack surface in scope, building a complete picture before any exploitation begins.
Manual exploitation. Our senior testers chain vulnerabilities by hand — going far beyond automated scanners — to prove real, demonstrable impact.
Analysis & reporting. Every finding is triaged, risk-rated with CVSS and written up with a copy-paste reproduction and clear remediation.
Remediation support & free retest. We support your team through the fixes and retest the remediated issues to confirm they are genuinely closed.
Tools & techniques
We test APIs manually using Burp Suite, Postman and custom tooling driven from your OpenAPI specification or captured traffic. We build a complete endpoint and authorization matrix, then attack object- and function-level authorization, token handling, mass assignment and rate limiting across every role. For microservice architectures we focus on the trust boundaries between services, where broken authorization most often hides.
When you need this engagement
For public, partner or internal APIs handling sensitive data
Before exposing a new API or major version to consumers
For microservice architectures with service-to-service trust
To meet API security requirements in SOC 2, PCI DSS or customer audits
What you receive
Full endpoint & authorization matrix
Findings with curl-based reproductions
Severity ratings and remediation steps
Free retest after fixes
What’s included in your report
Every api penetration testing engagement concludes with a comprehensive, board-ready report and a working session to walk your team through it. Your report includes:
An executive summary with overall risk posture for non-technical stakeholders
Detailed technical findings, each with a step-by-step, copy-paste reproduction
CVSS v3.1 severity ratings and business-impact context for every issue
Prioritized, actionable remediation guidance your engineers can apply directly
A complimentary retest to confirm fixes and update finding status
A formal attestation letter for customers, auditors and compliance programs
Standards & frameworks
OWASP API Security Top 10OWASP WSTGOWASP ASVSPCI DSS / SOC 2
Outcomes you can expect
After your api penetration testing, you will have clear, evidence-based visibility into your real security risk — not a scanner’s guesswork. You will know exactly which weaknesses an attacker could exploit, what the business impact would be, and the precise steps to fix them in priority order. Teams use our findings to close critical gaps, satisfy customer and regulator security requirements, and demonstrate due diligence to their board. With a complimentary retest included, you also get documented proof that the issues are genuinely resolved.
Engagement details & logistics
Every api penetration testing starts with a short, no-obligation scoping call to understand your goals, environment and constraints, followed by a fixed-price proposal and a clear statement of work. Most engagements are delivered fully remotely, with on-site work arranged where it genuinely adds value. Throughout testing we maintain an agreed communication cadence and escalate any critical, high-impact finding to you immediately rather than waiting for the final report. All work is performed under a signed NDA with strict data-handling controls, using safe, non-disruptive techniques and carefully coordinated rules of engagement to protect your production systems. On completion you receive your report and a walkthrough session, followed by a complimentary retest once your fixes are in place. Typical engagements are booked one to three weeks in advance, and urgent or pre-deadline testing can often be accommodated — just ask at hi@agentoffense.com.
Why organizations choose AgentOffense
Our api penetration testing is delivered by senior offensive-security engineers who test the way real attackers do — manually, creatively and with a relentless focus on proving genuine, demonstrable impact. Here is what sets our engagements apart:
Manual, exploit-driven testing that chains vulnerabilities the way a real attacker would, going far beyond what automated scanners can find.
Reproducible proof for every finding, with copy-paste reproduction steps your engineers can follow and independently verify.
Honest severity calibration so you invest in fixing what genuinely matters and avoid wasting effort on false positives and noise.
Clear, business-focused reporting that speaks to engineers and executives alike, tying every issue to real-world impact.
A complimentary retest included, so you get documented proof that your fixes actually close the attack path.
Responsible, collaborative delivery with a named point of contact and secure handling of all data throughout the engagement.
Explore related services
API Penetration Testing is frequently scoped alongside our other offensive-security services for broader coverage. Explore related engagements that complement it:
Web Application Penetration Testing — Manual web application penetration testing against the OWASP Top 10 and business-logic flaws. Exploit-driven testing with…
GraphQL Security Testing — Specialist GraphQL security testing — introspection abuse, query depth and batching DoS, authorization gaps per resolver,…
Mobile Application Penetration Testing — iOS and Android mobile application penetration testing — static and dynamic analysis, runtime instrumentation, secret extraction…
How much does API Penetration Testing cost?
Every api penetration testing is scoped and priced individually, so you pay for exactly the coverage you need — with no hidden extras. After a short, no-obligation scoping call we send a fixed-price quote, usually within one business day, with clear deliverables, a firm timeline and a complimentary retest included. The price of your api penetration testing depends on the size and complexity of the target and the depth of testing required, so you always know the cost up front before any work begins.
