Dependencies
SAST vs SCA
SAST finds flaws in the code your team writes. SCA finds known risks in the code your team depends on. They look at different code and catch different problems, so neither replaces the other.
Updated
The difference at a glance
| SAST | SCA | |
|---|---|---|
| Stands for | Static application security testing | Software composition analysis |
| Looks at | Your own source code | Open source and third-party components |
| Finds | Injection, unsafe input handling, insecure patterns | Known vulnerabilities, license issues, outdated packages |
| Relies on | Rules or models of what bad code looks like | Databases of published advisories |
| A finding appears when | Your code changes | A dependency changes, or a new advisory is published |
| Common noise | False positives on code that is actually safe | Real matches that do not affect how you use the package |
| Fix | Change your code | Upgrade or replace the component |
What SAST does
A SAST tool reads source code without running it and follows how data moves through it. If user input reaches a database query without being sanitized, it reports the file and line. Because it works on your code, it can find flaws nobody has ever published. It is also the source of the false positive complaints, since it reasons about what the code might do rather than what it does.
What SCA does
An SCA scan identifies the components in a project and looks them up in vulnerability and license data. It does not analyze your logic. It knows that a version has a published flaw, so its results are usually factual, but it says less about whether the flaw matters to you unless the tool adds reachability analysis. See what is software composition analysis for the full picture.
Why you need both
The two failures are independent. A codebase with no SAST findings can still ship a vulnerable dependency, and a clean dependency tree says nothing about a SQL injection in your own handler.
The timing differs as well. A SAST finding appears when someone changes code, so a pull request check catches most of them. An SCA finding can appear on a release you shipped months ago, the day a new advisory is published, with no commit to trigger anything. SCA therefore needs something that keeps checking what shipped.
Where DAST fits
Dynamic application security testing attacks a running application from the outside, the way a real attacker would. It finds what only shows up at runtime, such as authentication and configuration problems, without reading the code.
| SAST | SCA | DAST | |
|---|---|---|---|
| Needs | Source code | Manifests, images or a build record | A running application |
| Runs | On pull requests | On pull requests, in builds and after release | Against a test environment |
| Best at | Flaws in your code | Known risks in dependencies | Runtime and configuration flaws |
Which should you run first?
For most teams, SCA. It is quick to set up, it runs in seconds to minutes, and it covers the largest part of what you ship, because most of a modern application is dependencies. Add SAST next, on pull requests, and tune it to the rules that matter for your stack. Add DAST once you have a stable test environment to point it at.
Should you buy one platform or several tools?
Platforms such as Snyk, Checkmarx and GitHub Advanced Security bundle SAST and SCA, which means one contract and one workflow. Separate tools can be stronger in each area. What matters more is the input: both kinds of scanner work from what is declared or written, and neither sees what the build actually pulled in.
What neither one covers
SAST and SCA both read files. Neither observes the build, so code fetched by an install hook, packages restored from CI caches and the build tools themselves can stay out of view. That gap is what software supply chain security is about.
CRACI covers that part and leaves code scanning to the tools built for it. It does not do SAST or secrets scanning, by design, and plenty of excellent SAST tools work alongside it. It is a GitHub Actions runner that records what each job fetches into an SBOM and keeps checking the SBOMs of what shipped against new vulnerabilities. See the best SCA tools and where CRACI fits next to them.
SAST vs SCA: frequently asked questions
What is the difference between SAST and SCA?
SAST analyzes the code your team writes for flaws such as injection. SCA analyzes the open source and third-party components you depend on for known vulnerabilities and license issues.
Does SCA replace SAST?
No. They look at different code. SCA will not find a flaw in your own logic, and SAST will not tell you that a dependency has a published vulnerability.
What is the difference between SAST, DAST and SCA?
SAST reads your source code. SCA checks your dependencies. DAST tests a running application from the outside. Each finds problems the other two miss.
Is Snyk SAST or SCA?
Both. Snyk began with open source dependency scanning and also offers SAST, along with container and infrastructure-as-code scanning.
Is SonarQube SAST or SCA?
SonarQube is best known for static analysis of your own code, which is SAST. Check the current editions for what else they include.
Which comes first, SAST or SCA?
SCA is usually the quicker win because it is simple to set up and covers the largest part of what you ship. SAST takes more tuning to keep false positives down.
Cover what your scanners cannot see
Keep your SAST and SCA tools, and add a record of what each GitHub Actions build actually pulled in.
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