SAST, DAST and IAST are three ways to test an app, and each sees a different part of it. No single one catches everything, so the question is not which is best but when to use each. This is a plain comparison for mobile apps.
The three methods in one line each
- SAST (static) reads the app without running it.
- DAST (dynamic) runs the app and watches what it does.
- IAST (runtime) hooks into the running app to see its logic from the inside.
When to use each
| Method | Best at | Use it |
|---|---|---|
| SAST | Hardcoded secrets, weak settings, dangerous code patterns. | On every build. It is fast and cheap, so it belongs in the pipeline. |
| DAST | Insecure storage, cleartext traffic, broken certificate checks. | On important builds, where you need proof of runtime behaviour. |
| IAST | Logic and data flows that only show up at runtime. | When you need to understand why something behaves the way it does. |
Why you need more than one
Static analysis shows what an app can do; dynamic analysis shows what it does; runtime instrumentation explains how. Used together, they cover the file, the device and the network, which is the whole surface of a mobile app. Add a software bill of materials for the third-party code, and you have full coverage.
The practical setup is to run the fast static checks on every release and the deeper dynamic and runtime work on the builds that matter, all mapped back to OWASP MASVS.
Common questions
What is the main difference between SAST and DAST?
Do I need all three for a mobile app?
Which should I start with?
See it on one of your own apps
Mobexa tests the exact Android or iOS build you ship and maps every finding to the OWASP Mobile Top 10 and MASVS.
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