In most cases yes. SAST reads your code without running it, while DAST probes the running application from the outside. They see different things. SAST finds flaws that are visible in code. DAST finds problems that only appear at runtime, such as misconfigured servers, missing headers and broken session handling.
Definitions in one line each
SAST (static application security testing) analyzes source code or compiled code for security flaws. OWASP notes that it can run in the IDE or in CI and reports the file and line of a finding.
DAST (dynamic application security testing) scans a running web application, normally from the outside. OWASP lists issues such as cross-site scripting, SQL injection, command injection, path traversal and insecure server configuration as typical targets.
What SAST misses that DAST can see
OWASP lists several SAST weaknesses: it often misses configuration issues because they are not represented in code, it struggles with authentication, access control and cryptography misuse, and it can be hard to confirm that a flagged issue is real. A running scan sees the deployed result: the headers the server sends, the cookies it sets, the error pages it leaks, and whether a path that should need a login actually does.
What DAST misses that SAST can see
DAST only tests what it can reach. A page behind a flow the crawler never walked, or a code path that needs unusual input, may go unexamined. SAST reads every file it can parse, so it covers code that no test traffic has touched. It also tells the developer exactly which line to change.
Decision table
| Your situation | Suggested move |
|---|---|
| Internet facing web app or API, SAST already in CI | Add DAST against a staging copy |
| Internal batch job with no web surface | SAST and dependency scanning are usually enough |
| Many third party libraries | Add dependency scanning before DAST |
| Regulated buyers asking for dynamic testing evidence | Add DAST and keep the reports |
| No staging environment | Fix that first, then scan there, not in production |
How to add DAST without disruption
- Pick one application with a stable staging URL.
- Create a test account with realistic roles, and give the scanner its credentials.
- Run a first scan out of hours and watch for side effects such as test records piling up.
- Triage findings by whether they are reachable by a real user, then ticket the real ones.
- Schedule a recurring run and a quick run on release candidates.
Common mistakes
The most common mistake is treating the two as rivals and cutting one to save money. A better question is which gaps matter for your app. If your main risk is logic in your own code, SAST and review carry more weight. If your risk is a public facing service with many moving parts, dynamic testing earns its place. Whichever you add second, run it on the same applications as the first so you can compare findings and learn what each one contributes.
Try it yourself
Click through it at your own pace, or open it full screen.
Click through a web scan and note which findings come from runtime behavior rather than from code.
Where Safeguard fits
Safeguard handles SBOM and dependency scanning, reachability analysis and pull request policy gates. You can try a free scan on your dependencies.
Quick check
Can DAST replace SAST?
No. DAST cannot read code it never reaches, and it cannot point to a line to fix. Most programs run both.
Should I run DAST in production?
Prefer staging. Scans send hostile looking input and can create data or trigger alerts. If you must scan production, agree scope and timing first.
Sources
Last reviewed: 19 October 2026.
