The Complete and Practical Code Review Checklist

Introduction

A code review isn’t just about finding bugs — its main goal is continuously improving code quality.
A good code review should help you:

• Catch performance and security issues before release.
• Improve readability and maintainability.
• Keep team standards consistent.
• Prevent repeating the same mistakes.
• Share knowledge across the team.

In this post, inspired by the Neo Kim + CodeRabbit checklist and enhanced with process-oriented best practices, we’ll walk through a complete and practical approach you can apply in your projects.

🛠 Pre-Review Best Practices

Before you start reviewing someone’s code, set yourself up for success.

1. Understand the Context

• Read the PR description, linked issues, and related documentation.
• Understand why this change was made, not just what was changed.

2. Self-Review (For Authors)

• Review your own PR before asking others.
• Remove unnecessary changes, debug code, and commented-out blocks.
• Ensure tests pass locally.

3. Keep PRs Small

• Smaller PRs are easier to review thoroughly and faster to merge.
• If possible, break large features into smaller, reviewable chunks.

1️⃣ Functionality & Correctness

Ensures the code does exactly what it’s supposed to.

Checklist:

• Requirements: Does the code fulfill all feature and business requirements?
• Logic: Works for all expected inputs, including edge cases.

// Correct
if (user && user.isAdmin) { ... }

// Risky - may throw if user is null
if (user.isAdmin) { ... }

• Integration: Works without breaking existing features.
• Testing:
  • All unit tests pass.
  • Integration tests run successfully with real or mocked data.
• Edge Cases: Null, undefined, empty arrays, large datasets, unusual scenarios handled.

2️⃣ Readability & Clarity

Readable code is easier to maintain and less prone to bugs.

Checklist:

• Clarity: Easy to read and understand.
• Naming: Variables, functions, and classes have meaningful, descriptive names.

// Bad
const a = getData();

// Good
const userProfile = getUserProfile();

• Style: Consistent formatting (Prettier, ESLint, etc.).
• Comments: Explain “why” the code exists, not just “what” it does.
• Documentation: Updated and correct, especially for new APIs or modules.

3️⃣ Performance & Efficiency

Performance matters in every project.

Checklist:

• Algorithms: Use efficient algorithms and data structures.

// Bad - O(n^2)
arr.forEach(a => arr.forEach(b => { ... }));

// Good - O(n)
const set = new Set(arr);

• Scalability: Efficient with growing data size or user base.
• Bottlenecks: Avoid repeated computations or unnecessary operations.
• Reuse: Avoid code duplication; use shared functions/modules.
• Resources: Optimize CPU and memory usage.
• Caching: Reuse results to speed things up where appropriate.
• Compatibility: Works across supported browsers, devices, and platforms.

4️⃣ Security & Stability

Security should never be skipped.

Checklist:

• Validation: Sanitize and validate all inputs.
• Vulnerabilities: Guard against SQL injection, XSS, CSRF, and similar.
• Data: Handle sensitive information (passwords, tokens, PII) securely.
• Error Handling: Fail gracefully with clear, logged errors.

try {
  await processPayment();
} catch (err) {
  logger.error(err);
  throw new PaymentFailedError();
}

• Observability: Sufficient logging and monitoring in place.
• Compatibility: Works with older versions or required environments.
• API Design: Consistent, predictable, and easy to use.
• Dependencies: Use only safe and necessary libraries, updated to secure versions.

💬 Code Review Process Tips

Focus on Critical Issues First

Prioritize bugs, security risks, and performance issues before nitpicks.

Use a Constructive Tone

• Suggest improvements, don’t demand them.
• Use phrases like “What do you think about…?” or “Could we consider…?”

Be Specific

Link to documentation, examples, or patterns that support your feedback.

Follow Up

• After changes, verify all issues are resolved.
• Make sure no new issues have been introduced.

📋 Quick PR Review Checklist

A short version for quick checks in pull requests:

• Meets requirements without breaking existing features
• Clear and consistent naming, style, and documentation
• Efficient algorithms and resource usage
• Scalable and free of performance bottlenecks
• Secure input handling and data protection
• Proper error handling and observability in place
• PR is small, focused, and well-documented

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Conclusion

A good code review isn’t a bug hunt competition.
It’s an opportunity for team learning, quality improvement, and building trust in the codebase.

Remember: Code reviews are about progress, not perfection.

– Ramin ✌️