Understanding the difference between Dynamic and Static Application Security Testing—and when to use each.
Static Application Security Testing analyzes source code, bytecode, or binaries without executing the program.
Think of it as a code reviewer that reads every line looking for patterns that indicate vulnerabilities.
Dynamic Application Security Testing tests a running application by interacting with it like an attacker would.
Think of it as a security tester probing your live application for real exploitable vulnerabilities.
| Aspect | SAST | DAST |
|---|---|---|
| What It Analyzes | Source code, bytecode, or binaries | Running application via HTTP requests |
| When It Runs | During development, in CI/CD | On deployed application (staging/production) |
| Access Required | Source code access | Only URL of running application |
| Finds | Potential vulnerabilities in code patterns | Actual exploitable vulnerabilities |
| False Positives | Higher - can't verify exploitability | Lower - tests actual behavior |
| Coverage | All code paths, including unreachable | Only what's exposed and reachable |
| Language Dependency | Requires language-specific rules | Language agnostic |
| Setup Complexity | Needs code integration | Just point at URL |
Catch issues as you write code. Fast feedback helps fix problems immediately.
Verify the deployed application is actually secure, not just the code.
When you don't fully understand the code, test actual behavior.
SAST on PRs, DAST on staging deployments.
No source access needed. Test what matters: runtime behavior.
Many compliance frameworks require both approaches.
VAS uses DAST approaches to find real vulnerabilities in your running application. No source code required—just your URL.
Free Security ScanNeither is universally better—they serve different purposes. SAST is better for early detection during development. DAST is better for validating actual security of running applications. Most security programs use both for comprehensive coverage.
Not entirely. DAST can't analyze code you don't execute, so logic vulnerabilities in rarely-used features may be missed. SAST also provides faster feedback during development. However, DAST is more reliable for validating real-world security.
DAST is often better for vibe-coded apps because you may not fully understand the generated code. DAST tests actual behavior regardless of code complexity. VAS uses DAST approaches to find real vulnerabilities in your deployed app.
IAST (Interactive AST) combines aspects of both—it instruments running apps to monitor code execution during testing. RASP (Runtime Application Self-Protection) monitors production apps. Both add runtime insight but require application modification.
1) SAST during development for immediate feedback, 2) SAST in CI/CD as a gate, 3) DAST on staging before production, 4) Periodic DAST on production to catch configuration drift.
Last updated: January 16, 2026