Static vs dynamic testing
Static testing checks the work without running it. Dynamic testing runs the software and checks the result. You need both, at different stages.
By Quality AboveAll · June 28, 2026 · 5 min read
Where this fits in the wider picture.
Static vs dynamic testing
Senior people on the actual work
No layered account teams between you and the build.
Designed for the bad day
Failover, retries and load behaviour proven before launch.
Threat modelled from the start
Secure defaults, dependency hygiene, and audit trails.
Budgets, not guesses
Latency and throughput targets set and measured.
Usable by everyone
WCAG 2.2 checks built into the pipeline.
Static testing finds defects by examining code and documents without running them, while dynamic testing finds defects by running the software and watching what it does.
What sets them apart
Static testing does not execute the program. You read, review, and analyse. Requirements, design docs, and source code all get checked while they sit still.
Dynamic testing executes the program. You give it inputs, run it, and compare the actual output against the expected one. The software has to be running for this to happen.
- Static: reviews, walkthroughs, and automated code analysis.
- Dynamic: functional runs, load runs, and user acceptance.
A worked example: one login function
Picture a new login function. Static testing happens first. A reviewer reads the code and spots that the password is logged in plain text, and that one error branch has no message. No code ran, yet two real defects are found.
Dynamic testing happens next. The team runs the function with a valid password, a wrong password, and an empty field, then confirms each response. This catches a bug the review missed: the account locks after two failed attempts instead of five.
Neither pass alone would have caught both faults. That is the point.
Static testing asks whether the work looks right. Dynamic testing asks whether the work behaves right.
Why static testing saves money
Static testing finds defects early, often before a single line runs. A bug caught in review costs far less than the same bug caught in production, because nothing has to be rebuilt or redeployed.
Static work fits neatly into a pipeline through CI/CD test integration, where linters and analysers scan every commit. Dynamic work then runs the actual suites, from manual testing to load and stress testing. Tools such as Playwright and Selenium drive the dynamic side.
The honest caveat
Static testing has a hard limit. It cannot see runtime behaviour. Timing bugs, memory leaks, and integration failures only appear when the code actually runs, so a clean review is never proof of a working feature.
The reverse is also true. Dynamic testing can miss a security flaw that a careful human read would have caught in seconds. That is why we pair the two, with senior reviewers on the static side and real execution on the dynamic side, across financial services and healthcare work. You can see how both fit our flow on the process page.
If your team leans hard on one side and neglects the other, that gap usually shows up as late, expensive bugs. A free 30-minute testing audit will show you which side needs attention first.
Questions about this topic.
What is the difference between static and dynamic testing?
Static testing examines code and documents without executing them, through review and analysis. Dynamic testing runs the software and observes behaviour. Static finds defects earlier; dynamic finds what only appears at runtime.
Is code review a form of testing?
Yes, it is the most common static technique and one of the most cost-effective. Defects caught in review never reach a test environment, so they never consume a debugging cycle.
Which should come first?
Static, because it is cheaper and earlier. Static analysis and review on every change, then dynamic testing for behaviour that cannot be assessed by reading.
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