Code review: Detecting quality problems early [2026]

**Code reviews are one of the most effective methods to identify quality problems before becoming expensive bugs. ** Studies show that code reviews can find up to 60% of the errors – and this would lead to a fraction of the costs that would cause a later error fixation. But not every code review is equally effective. This article shows how to get the maximum out of your reviews.

Why code reviews are indispensable

Advantage Description

**Bugs are found before they go to production **The team learns from each other and understands the entire code ConsistencyUniform coding standards are enforced MentoringJunior developers learn from experienced colleagues DocumentReview comments serve as additional documentation

The code review checklist

Functionality

• Does the code meet the requirements?

• Are all edge cases treated?

• Is there potential zero pointer extracts?

• Are errors properly treated?

Readability and Wartability

• Are variables and method names meaningful?

• Is the code self-explanatory or does it need comments?

• Is there unnecessary complexity?

• Does the code follow the coding standards?

Performance and Security

• Are there obvious performance problems?

Are SQL-Queries protected against injection?

• Are sensitive data handled safely?

• Is there Memory Leaks?

Example: Before and After

** Problematic code:**

function calc(a,b,c) { var x = a * b; if(c == true) x = x * 1.19; return x; }

After review:

function calculateTotalPrice(quantity, unitPrice, includeTax) { const TAX RATE = 0.19; let subtotal = quantity * unitPrice;

if (includeTax) { return subtotal * (1 + TAX RATE); } return subtotal }

Recommended tools

SonarQube

Automatic code analysis and quality metrics

GitHub/GitLab

Integrated pull-request reviews

ESLint/Prettier

Automatic Style Checks for JavaScript

Crucible

Dedicated code review tool by Atlassian

"Code reviews are not a criticism of the developer, but an investment in the quality of the product. "

Best Practices for Effective Reviews

• Small changes: Review You maximum 200-400 lines at once

• Time limit: Not longer than 60 minutes on the review

• Constructive feedback: Criticize the code, not the developer

• Automatization: Let tools take over simple checks

• Checklists: Use standardized checklists

Do you need an external code review?

Our experts analyze your code and identify quality problems. Request Code Review

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• Technical debt: The silent killer

• Yeah. The 5 most common errors in software development

• Agile's project management at [software maintenance](/services/software recovery)

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