Application and API security testing for a SaaS platform

The client is a US retail SaaS provider whose web application and public APIs sit between shoppers and a large merchant base. For a platform that handles orders and customer data at scale, a single exploitable weakness can expose thousands of accounts at once.

The product shipped fast on a frequent release cadence, and security assurance had never kept pace with the pace of engineering.

The platform had grown feature by feature with no systematic security review, so nobody could say with confidence which endpoints were exposed or how they behaved under abuse. Coverage was assumed rather than evidenced.

Previous scans had produced raw tool output that developers could not act on, so findings piled up unread and unresolved. A scanner dump is not the same as an actionable result.

With enterprise buyers now demanding proof of security testing before signing, the client needed risk-rated, remediation-ready findings, not another export. The report had to satisfy both engineers and procurement.

We agreed a signed scope and rules of engagement first, then tested the application and APIs methodically against the OWASP Top 10 and ASVS. Working to a repeatable checklist is what turns coverage from ad hoc into systematic.

We combined automated scanning with manual validation, confirming exploitability on the highest-risk paths so severities reflected real impact rather than theoretical flags. Manual verification is what separates a true finding from noise.

Every issue shipped with reproduction steps, business impact, and remediation guidance mapped into the client's tracker, and we retested each fix to prove the risk was genuinely closed. The engagement ended with evidence, not a backlog.