Qodana / Static Code Analysis Guide / Automated Code Review versus Manual Code Review

Automated Code Review versus Manual Code Review: Why Smart Teams Use Both

Every developer knows the sinking feeling of finding a critical bug after it’s already in production. Manual code reviews catch a lot, but they can miss what automated tools spot instantly. Automated reviews, on the other hand, can’t replace the nuanced judgment of a human eye.

So, which should you trust more: a teammate combing through your pull request, or a static analysis engine running at machine speed (static analysis can scan 100k+ lines of code in seconds)? The truth is, both have strengths, and knowing when to use each could mean the difference between shipping clean code or finding fixes.

Jeff Atwood
Co-Founder of Stack Overflow

“You’ll quickly find that every minute you spend in a code review is paid back tenfold”.

What’s the difference between static code analysis and code review?

Both manual code review and automated code review aim for the same goal: catching problems before they become expensive mistakes - but they take different paths to get there.

Manual code review is a human-led process where one or more developers examine code changes line by line, looking for logical errors, architectural missteps, unclear naming, and deviations from team conventions.

Automated code review, on the other hand, uses static code analysis to scan source code without executing it. These tools apply a consistent set of rules to detect bugs, vulnerabilities, and code smells automatically.

At JetBrains, we see these approaches as complementary, especially when they’re in the same workflow. Manual review offers nuance and mentorship; static analysis delivers speed and consistency. Together, they create an important safety net for development teams that covers a broad spectrum of risks.

Why human minds still matter: The strengths of manual code review

One of the greatest advantages of manual code review is context. A human reviewer can understand why a piece of logic exists, not just whether it’s syntactically correct. They can spot design patterns that might lead to problems months down the line, or identify opportunities to simplify code in ways automated tools can’t fully grasp.

Manual review is also a powerful channel for knowledge sharing. When a senior developer reviews a junior colleague’s pull request, it’s not just about finding mistakes — it’s a chance to mentor, explain reasoning, and help them grow. For distributed teams, these moments can be invaluable in building trust and alignment.

But don’t rely on manual code reviews alone

Manual review is rarely quick. In large projects, a single pull request might take hours to review thoroughly, and that can delay delivery. And because it’s a human process, it’s vulnerable to oversight, even the most experienced reviewers can miss subtle issues, especially when reviewing repetitive boilerplate or under tight deadlines.

In Microsoft’s research report, Expectations, Outcomes and Challenges of Modern Code Review, it states: “There is a mismatch between the expectations and the actual outcomes of code reviews. From our study, review does not result in identifying defects as often as project members would like and even more rarely detects deep, subtle, or ‘macro’-level issues.”

Consistency is another challenge. Different reviewers may have different priorities or tolerances for “good enough” code, leading to uneven quality standards over time.

This is where automated review can pick up the slack, enforcing rules objectively and at scale. For example, Qodana could flag this risk automatically:

// Potential null pointer issue
String name = user.getName().toUpperCase(); // NPE risk

Catching what humans miss with automated static code analysis

Automated review through static code analysis excels at speed and reliability. Tools like Qodana can scan an entire codebase in seconds, flagging potential bugs, performance issues, security vulnerabilities, and style violations, all before code is merged.

Automation also ensures that every change is evaluated against the same rules, every time. There’s no risk of a reviewer missing an error because they’re tired or distracted. For security-conscious projects, static analysis can run checks against OWASP recommendations or licensing requirements automatically.

And because Qodana integrates seamlessly with CI/CD servers like TeamCity, these scans can become a natural part of the build process, blocking poor-quality code before it ever reaches production.

Qodana static code analysis report showing unused declarations detected in a project.

The challenges of automated code reviews

Automated review isn’t perfect. It lacks the contextual judgment of a human reviewer, so it might flag code that is technically unconventional but still the best choice for a specific problem. These “false positives” can lead to alert fatigue if not managed carefully.

There’s also the matter of rule maintenance. Over time, teams may need to update or fine-tune their analysis rules to reflect new frameworks, coding standards, or regulatory changes. JetBrains tools make this easier by allowing teams to share and version-control their inspection profiles, ensuring the rules evolve alongside the codebase.

When to use static code analysis over manual review, or with it

Static code analysis is especially valuable when working on large, fast-moving projects where manual review alone can’t keep pace. It’s also indispensable in environments where security is paramount, such as fintech or healthcare, where every commit must pass a consistent compliance check.

It can also accelerate onboarding. New team members can run automated scans locally and learn team coding standards through real, contextual feedback before their code even reaches a reviewer. For example, Qodana’s local analysis mode integrates with JetBrains IDEs, so developers see potential issues as they type, reinforcing good habits early.

Finally, in continuous integration pipelines, static code analysis acts as a guardrail. It ensures that no matter how quickly code is being delivered, it never bypasses essential quality or security checks.

Manual code review and automated static analysis each bring unique strengths to the table. Manual review offers deep understanding, architectural insight, and knowledge sharing. Automated review delivers speed, scalability, and consistent enforcement of rules.

In short: automation accelerates you, but people give you perspective

Automated tools are great at catching null dereferences, memory leaks, SQL injection patterns, unused variables, and dependency vulnerabilities as just a few examples. However, manual review excels at: API design, readability, naming consistency, adherence to domain-specific patterns.

By combining both, teams can catch more issues, reduce technical debt, and release cleaner, safer code faster.Automation accelerates you, but people give you perspective. The best pipelines have both.

Add static code analysis to your CI pipeline, as well as license and security checks.

Qodana