SAST vs DAST: Which Security Testing Approach Does Your App Need?

Static Application Security Testing (SAST) analyses your source code without executing it, looking for patterns that indicate vulnerabilities — SQL injection, hardcoded secrets, insecure deserialization, and so on. It runs fast, integrates into your CI pipeline, and catches issues before a single line reaches production. The tradeoff: SAST produces false positives, and it cannot detect vulnerabilities that only emerge at runtime.

Dynamic Application Security Testing (DAST) does the opposite: it fires HTTP requests at a running application and analyses the responses for signs of exploitable behaviour. DAST is slower, requires a deployed environment, and has less visibility into your code — but it catches things SAST never will, like authentication flaws, session management issues, and misconfigured headers.

Most mature security programmes use both. SAST in your PR checks catches the low-hanging fruit early and cheaply. DAST in your staging environment — automated weekly, and manually before any major release — finds the runtime surprises. Adding dependency scanning (Snyk, OWASP Dependency-Check) rounds out the picture by surfacing vulnerabilities in your third-party packages.

If you are choosing between the two, start with SAST: the feedback loop is faster, the developer experience is better, and the cost per finding is lower. Once your codebase is reasonably clean on static findings, add DAST. The goal is defence in depth — no single tool catches everything, and that is by design.