SAST vs DAST: Which Application Security Testing Is Right for You?
SAST and DAST are complementary application security testing methods. SAST analyzes source code without executing it, while DAST tests running applications by simulating attacks. Most mature AppSec programs use both alongside SCA and IAST tooling.
Detailed Comparison
Approach
Inspects source code, bytecode, or binaries without running the application — "white-box" testing.
Tests the running application from the outside, simulating attacker behavior — "black-box" testing.
When in SDLC
Runs early in development, often integrated with IDEs, pre-commit hooks, or CI on every push.
Runs against deployed environments — staging, QA, or production-equivalent — typically nightly or pre-release.
What It Finds
Insecure coding patterns, hardcoded credentials, taint flow issues, SQL injection sinks, weak crypto APIs.
Runtime vulnerabilities, authentication flaws, session management issues, business logic flaws, exploitable configurations.
False Positives
Higher false positive rate because it lacks runtime context — must be tuned to your codebase.
Lower false positive rate — if a payload triggers a vulnerability, it almost always indicates a real issue.
Language/Stack
Language-specific — needs separate engines for Java, Python, JavaScript, .NET, Go, etc.
Language-agnostic — works on any application that responds to HTTP/API requests.
Coverage
Can analyze 100% of code paths, including unused branches and rare conditions.
Limited to code paths reached by the crawler or test cases — less coverage of edge logic.
Speed
Fast on small codebases, slow on large ones; incremental scanning helps in CI.
Variable — quick scans take minutes, deep authenticated scans of large apps take hours.
Cost Model
Typically licensed per developer or LOC; commercial tools $50-$500 per developer per year.
Typically licensed per application or per scan; commercial tools $5,000-$50,000+ per year.
Compliance Mapping
Required by PCI DSS 6.3, satisfies ISO 27001 A.8.28 secure coding controls.
Required by PCI DSS 6.4 web application testing, satisfies SOC 2 Common Criteria 8.1.
Best For
Catching vulnerabilities before they ship, secure coding training feedback loops, and compliance evidence.
Validating that runtime defenses work, finding configuration issues, and simulating real attack paths.
Our Recommendation
Use both SAST and DAST in a layered AppSec program. SAST catches issues before code ships and is cheaper to remediate; DAST catches what only manifests at runtime and validates your deployed posture. For PCI DSS, ISO 27001, and SOC 2 compliance, both are typically expected.
Frequently Asked Questions
No. DAST is automated and finds known vulnerability classes; manual penetration testing finds business logic flaws, chained exploits, and creative attack paths that automated tools miss. Most compliance frameworks require both.
Start with SAST integrated into CI — it catches issues cheaply and trains developers in secure coding. Add DAST as the application matures and you have stable staging environments. Free tools like Semgrep (SAST) and OWASP ZAP (DAST) cover most early-stage needs.
IAST (Interactive Application Security Testing) instruments the running application during functional testing — combining SAST visibility with DAST runtime context. It produces fewer false positives but requires deployment of an agent and works best in QA environments.
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Need Help Deciding?
Our cybersecurity experts can evaluate your specific situation and recommend the right approach for your organization.