Certified auditors test your APIs the way attackers do, then give you a prioritized plan to fix what we find.
Get Your QuoteAn API security audit from Altius IT is a controlled, real-world assessment of your REST, GraphQL, and SOAP APIs performed by Certified Information Systems Auditors (CISA). Sometimes called a web API security audit, this assessment covers any HTTP-based API your organization exposes. We combine API penetration testing with configuration and documentation review, testing every authorization boundary against the OWASP API Security Top 10. APIs now carry most application traffic and most application breaches, and they fail in ways traditional web testing does not catch. You receive a risk-rated report with step-by-step remediation guidance, an Auditor Opinion Letter you can share with clients, and 90 days of free post-audit support.
Testing a full web application with a user interface? See our web application security audit, which includes the APIs your application uses.
Our API security testing follows the OWASP API Security Top 10, combining automated scanning with manual penetration testing to find the authorization and business logic flaws that scanners miss:
Each API style fails differently, and we test each accordingly.
Webhooks and event-driven integrations are tested for forgery, replay, and signature validation.
A structured, four-phase approach that maps your API attack surface, tests every authorization boundary, and leaves your team with a clear remediation plan.
We review your OpenAPI/Swagger or GraphQL schema where available, map undocumented and deprecated endpoints, and build a complete inventory of your API attack surface. No documentation? We discover and map endpoints through traffic analysis and enumeration.
We build a matrix of every role against every endpoint and method, then systematically test each boundary for horizontal and vertical privilege escalation. This is where most critical API findings come from, and it cannot be automated reliably.
Authentication and token testing, injection and fuzzing across parameters and payloads, rate limit and abuse testing, and configuration review of gateways, CORS, and error handling. Testing is coordinated with your team and scheduled to avoid disruption to production operations.
We deliver a report with prioritized findings, risk ratings, and specific remediation steps for each vulnerability. We then walk your team through the results and remain available for 90 days of free post-audit support. Retesting of remediated findings is available.
| API-Only & Headless Products | Where the API is the product, including SaaS platforms and developer tools. |
| Mobile App Backends | Often the weakest link because the API trusts the app. Pair with our mobile application security audit for full coverage. |
| Partner & B2B Integrations | Integrations that expose data to third parties under contractual security obligations. |
| Microservices Architectures | Where internal service-to-service trust is rarely tested. |
| Payment, Healthcare & Financial APIs | APIs subject to PCI DSS, HIPAA, and related regulatory requirements. |
We benchmark your API security against recognized frameworks and map findings to the requirements that matter to your business. API findings are a frequent gap in customer security reviews and vendor assessments; the audit report and Auditor Opinion Letter give you documented, independent evidence to close it.
Every finding includes a risk rating, evidence, and detailed instructions to mitigate or eliminate the issue, mapped to the OWASP API Security Top 10.
As Certified Information Systems Auditors, we can issue an Auditor Opinion Letter stating your systems meet security and compliance requirements. Share it with partners and enterprise customers who ask for proof of API security.
Ask questions, validate fixes, and get guidance from the same team that performed your audit.
Each audit is staffed with:
Anyone can call themselves a security consultant. Altius IT is certified as a Certified Information Systems Auditor (CISA) to audit your environment and issue formal reports and recommendations. Our experts have appeared on national television and in more than 40 publications.
Strengthen your APIs against evolving threats and protect the data behind every integration.
Meet PCI DSS, HIPAA, GDPR, SOX, NIST, and ISO 27001 compliance standards.
Safeguard sensitive data, intellectual property, and customer information.
Every engagement includes follow-up support to ensure vulnerabilities are properly mitigated.
Answers to common questions about our API security audit and penetration testing services.
An API security audit is an independent assessment of your APIs' authentication, authorization, data handling, and configuration, combining automated scanning with manual penetration testing against the OWASP API Security Top 10. The result is a risk-rated report with specific remediation steps for each finding.
Web application testing focuses on the user interface and browser-based attacks. API testing focuses on direct endpoint access, where attackers bypass the interface entirely: object-level authorization, token handling, mass assignment, and rate limiting. Most critical API flaws, such as BOLA, are invisible to traditional web scanners.
Yes. GraphQL testing covers introspection exposure, query depth and complexity abuse, batching attacks, and field-level authorization, in addition to standard authentication and injection testing.
Yes. While OpenAPI/Swagger specifications speed up the engagement, we discover and map endpoints through traffic analysis and enumeration when documentation is unavailable. Undocumented and forgotten endpoints are often where the most serious findings live.
Yes. Mobile backends are a core use case for API security audits, since the API often trusts the mobile client more than it should. We test the backend directly, and we can combine the engagement with a mobile application security audit of the client apps.
Most engagements take two to four weeks from kickoff to final report, depending on the number of endpoints, roles, and API styles in scope. We confirm the timeline in your proposal before work begins.
Cost depends on the number of endpoints, authentication roles, and API styles in scope. We provide a fixed-fee quote after a scoping call, so you know the full cost before work begins.
No. Testing is scheduled and coordinated with your team, intrusive techniques are agreed upon in advance, and rate-limit testing is performed carefully. We can test staging environments where preferred.
At minimum annually, and after any major release, new integration, or security incident. Because APIs change frequently, organizations with active development often test more frequently. Many compliance frameworks, including PCI DSS, require testing at least annually and after significant changes.
Strengthen your APIs against evolving threats, meet partner and regulatory requirements, and protect the data behind every integration.
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