12 Best Practices for Better Code Reviews
Quality feedback is essential in virtually any creative endeavor, and we’d certainly consider software programming a creative endeavor.
That’s why establishing and optimizing a code review process is vital to the health of your overall software development lifecycle. Code reviews suit professional development, software quality, application security, and your team’s overall growth and performance.
Leveraging the right code review tools, such as GitHub or automated linters, can further streamline the process and make it more efficient and impactful.
Code review proponents cite a stat from Steve McConnell's book Code Complete, which says that comprehensive code inspections unearthed around 60% of defects, compared with 25-45% in standard checks.
In this article, we’ll unpack the keys to an intense code review process and offer expert advice on how to do it right.
Why Are Code Reviews Important?
In a sense, the importance of code reviews speaks for itself: the process is all about improving software quality, reliability, and business outcomes – while conversely reducing defecting, security issues, technical debt, and other potential problems.
However, according to Mike Stone, co-founder of The Gnar Company, a custom web and mobile development firm based in Boston, they can be part of a healthy organizational culture overall.
Stone says his firm operates with a mantra of “engineers, but human” to proactively counter some negative assumptions about developers’ ability to work well with others.
“It’s a nod both to our collaborative nature and our commitment to defying the dreaded “working with developers” stereotype,” Stone tells The CTO Club. “Our code review process is not an afterthought, nor a bonus task, but an integral part of our process and culture.”
Code reviews give the team a regular mechanism for communicating and collaborating.
“As we review and celebrate each other’s code, we grow our sense of mutual responsibility and collective ownership over the work we do,” Stone says.“We also take pride in our continued dedication to a job well done."
Types of Code Reviews
Code review processes can look different across teams and organizations - many DevOp testing books explain this obvious fact. However, you can group many of them into two categories, which aren’t mutually exclusive.
- Formal Code Reviews: These are structured sessions where developers present their code changes to peers for review and comment. This type often involves detailed inspection, discussion, and documentation. Formal reviews are thorough but can be time-consuming and stressful if you don’t have a healthy culture. (A positive, blameless culture should mitigate that.)
- Tool-Assisted Reviews: Developers submit their pull requests for review using platforms like GitHub, GitLab, or Bitbucket. These tools facilitate inline commenting, automated checks, and version control, making the process more efficient and trackable.
Tool-assisted reviews are sometimes grouped under a broader umbrella of “lightweight” code reviews or code review processes that are less formal and often less time-consuming. Other examples of lightweight code review processes include pair programming, a DevOps best practice in which two developers collaborate: one writes code, and the other reviews it while they work.
Deciding which type(s) of code reviews are best for your team is an essential early step.
10 Top Code Review Tools
Here's my pick of the 10 best software from the 10 tools reviewed.
Key Players in Code Reviews
Another essential early step is identifying the right team members for the right roles in your code review process. The specific people will vary somewhat depending on the makeup of your team, but developers – or anyone who writes code in your org – should be on the list. (Duh.)
Other possibilities include roles like Site Reliability Engineers, DevOps engineers, security engineers, and anyone interested in positive, blameless code reviews to improve software quality.
No matter their role or person, code review participants generally fall into two categories: authors (the people writing the code) and reviewers (the people reviewing that code). Later in the article, we’ll share some advice for both roles.
12 Best Practices for More Productive Code Reviews
“Overall, code reviews help create a culture of continuous improvement and shared responsibility for code quality, which ultimately leads to more reliable and maintainable software,” says Derek Ashmore, Application Transformation Principal at the cloud consulting firm Asperitas.
There’s no guarantee of that outcome – just telling one developer to review another developer’s code isn’t likely to produce optimal results. Common challenges include inconsistent or sparse feedback, personal biases, and competing priorities or time constraints that make code reviews feel like a burden.
To prepare for success, Ashmore and Stone suggest tips and best practices for implementing or improving your code review process.
1. Focus on the Code, Not the Person
“Always review the code, not the developer,” Ashmore says.
Strive to make feedback objective, respectful, and constructive. Petty or personal criticisms can undermine the whole process. It’s not a “gotcha” game.
2. Set Clear Guidelines and Standards
It’s almost possible to have positive, productive code reviews when participants don’t know the goals or standards that they’re working towards. Learning how to improve software quality should be a standard process.
Leadership should set the right tone early and recalibrate as needed. Clear communication is a must.
“Ensure all team members know the coding standards and guidelines,” Ashmore says. “This includes naming conventions, formatting, and architectural best practices. Reviewers should be aligned on these to provide consistent feedback.”
3. Limit the Scope of Each Review
You’ve probably heard the phrase “don’t try to boil the ocean” and its variants. The principle applies here: asking people to do too much in a single review can lead to mistakes and resistance from people with many other responsibilities.
“Reviewing large pull requests can be overwhelming and prone to oversights,” Ashmore says. “Smaller, focused reviews are easier to manage and more effective. Aim to review manageable chunks of code, typically no more than 200-400 lines.”
4. Give Feedback on Structure and Logic First
Ashmore also recommends addressing structural and logical issues before moving on to minor details like style and formatting.
"This ensures that the foundational aspects of the code are solid before you dive into nitpicks,” he says.
5. Use Automation for Routine Checks
As many other repetitive IT processes do, automation can be a significant time-saver. This is one way tool-assisted reviews can augment (rather than replace) formal, human-led reviews.
“Automate checks for style, formatting, and other simple conventions using tools like linters or CI pipelines,” Ashmore says. “This saves reviewers time and lets them focus on more critical issues like code logic and structure.”
6. Encourage Descriptive Commit Messages
“Ask developers to write clear and descriptive commit messages,” Ashmore advises. “This provides context for each change, making the review process smoother and helping future team members understand the history of the code.”
Details from authors are critical, especially if someone from outside the project will be reviewing them. "Not only does it give reviewers full context—what’s changing and why—but it also allows them to learn from the author’s work,” says Stone.
“For reviewers, detail plays an equally important role. It helps the author understand the purpose of a suggestion, whether it’s a minor nitpick or a critical issue that could break something.”
7. Ask Clarifying Questions
Encourage questions as a key mechanism for generating productive feedback. A question allows the author-developer to reflect and respond meaningfully rather than get defensive. It also will enable reviewers to better understand previous choices rather than making assumptions.
“Questions can lead to better understanding and allow the developer to explain their reasoning or consider alternative approaches,” Ashmore says.
Similarly, Stone recommends reviewers avoid dogmatic beliefs or statements in their feedback. Unless a particular line of code is going to break something, treat feedback as suggestions rather than mandates.
“Instead of saying ‘do this’ or ‘do that,’ we stick to a more open, collaborative, brainstorming-style approach," Stone says. “[Try] ‘what do you think of this?’”
8. Look for Potential Issues, Not Just Bugs
Some code reviews focus narrowly on actual bugs or defects. That’s fine, but it might be too limited in scope. Holistic code reviews can also look for edge cases, performance implications, and scalability issues.
They can also be an opportunity to address technical debt – those trade-offs made previously to hit a deadline or other goal.
“Good code reviews go beyond just spotting bugs and involve thinking about how the code will behave in various scenarios," Ashmore says.
9. Encourage Test Coverage
“Ensure that new features or changes include appropriate tests,” Ashmore says.“Encourage adding unit tests and integration tests as relevant to help catch bugs and document expected behaviors.”
10. Be Timely and Responsive
Ashmore also recommends time-boxing your reviews and setting deadlines for feedback, such as 24 hours or another reasonable timeframe:
“Quick feedback helps maintain momentum. Additionally, respond to any questions or clarifications from the developer promptly.”
11. Balance Praise and Critique
Both Ashmore and Stone emphasize the value of positive feedback and celebrating wins – not simply criticizing or pointing out defects. Doing so is key to continuous improvement and reinforcing the best practices and positive outcomes.
“Don’t forget to recognize good work,” Ashmore says.
Doing so is key to continuous improvement and reinforcing the best practices and positive outcomes.
“Celebrating each other’s moments of brilliance, no matter how big or small, is validating, motivating, and inspiring,” Stone says.
“Positive comments like ‘TIL’ (today I learned…) or ‘This is sweet! How does it work?’ reinforce positive behavior, bring smiles to our faces, and reiterate the purpose behind the review process.”
12. Document and Share Learnings
Documentation is good, especially when it helps identify and solve recurring issues or helps quickly bring new team members up to speed.
“When recurring issues or patterns emerge, document them for future reference,” Ashmore says. "Consider creating a shared repository of review checklists, guidelines, and common issues to help streamline future reviews.”
While comments are suggestions and not rules, it’s still essential for authors to close the loop by acknowledging reviewer comments.
Stone adds, "This ensures all feedback has been seen, addressed, and considered. It also fosters further conversation and knowledge transfer, which are essential to continuous improvement.”
Code Review Metrics
Measuring the effectiveness of code reviews is essential for maintaining code quality, improving review efficiency, and optimizing development workflows. Without tracking objective metrics, teams may struggle to identify bottlenecks, evaluate progress, or ensure consistency in the review process.
Implementing measurable standards helps teams refine their approach, allocate resources effectively, and enhance collaboration.
Common Code Review Metrics
Tracking key metrics provides insights into how sound code reviews are conducted and highlights areas for improvement. Some of the most commonly used code review metrics include:
- Defect Density – Measures the number of defects found per unit of code. This is calculated by dividing the defect count by thousands of lines of code (kLOC). A higher defect density may indicate poor code quality, while a lower density suggests fewer errors and better adherence to coding standards.
- Defect Rate – Calculates how frequently defects are identified in the review process. This is determined by dividing the defects by the total hours spent reviewing the code. Monitoring this metric helps teams assess whether their review process is thorough and effective.
- Inspection Rate – Measures how quickly a team reviews a specific amount of code. This is determined by dividing the total lines of code (LoC) reviewed by the number of inspection hours. A balance should be struck between efficiency and thoroughness to avoid rushed or ineffective reviews.
- Review Coverage – Indicates the percentage of code changes that undergo peer review. A higher review coverage ensures that all critical updates receive proper scrutiny, reducing the likelihood of undetected bugs.
- Time to Review Completion – Measures the time it takes for a pull request or submitted code change to go through the entire review process. Shorter review times help maintain project momentum, but excessively quick reviews may lead to oversights.
- Rework Rate – Tracks how often code changes require modifications after a review. A high rework rate could indicate unclear requirements, poor initial code quality, or inconsistent review feedback.
The Impact of Code Review Metrics on Process Improvement
By analyzing these metrics, teams can identify inefficiencies, improve collaboration, and make data-driven decisions about their development workflow. Some ways that metrics drive process improvement include:
- Identifying High-Risk Components – Defect density helps pinpoint areas in the codebase that are more prone to errors. Teams can allocate additional resources or implement stricter review processes in these areas to improve quality.
- Optimizing Review Efficiency – Monitoring inspection rate and time to review completion helps teams balance speed and accuracy, ensuring code reviews don’t become bottlenecks while maintaining thoroughness.
- Enhancing Code Quality – Tracking defect rates and rework rates allows teams to refine coding standards, enforce best practices, and improve initial code submissions.
- Streamlining Collaboration – Ensuring a high review coverage rate fosters team accountability and shared ownership of the codebase, leading to better long-term maintainability.
By incorporating structured code review metrics, development teams can continuously refine their review processes, reduce defects, and create more reliable software. Making these metrics a regular part of development ensures that code reviews remain effective, transparent, and aligned with project goals.
Security Vetting in Code Reviews
Security is a fundamental aspect of software development, and code reviews are important in identifying and mitigating potential vulnerabilities before they make it to production. A dedicated security vetting process ensures that code is functional, efficient, and resistant to exploits, data breaches, and unauthorized access.
Key Areas of Security Vetting
Security-focused code reviews examine the code for vulnerabilities, misconfigurations, and compliance issues. Some of the most common security risks to look for include:
- Injection vulnerabilities – Checking for SQL injection, command injection, and other attack vectors where user input is improperly handled.
- Hard-coded credentials – Identifying sensitive data such as API keys, passwords, and encryption keys that should not be stored directly in code.
- Insecure authentication and authorization – Ensure access control mechanisms are correctly implemented, and user authentication processes are secure.
- Improper error handling – Reviewing error messages to prevent leaking sensitive system details to end users.
- Inadequate encryption – Verifying that sensitive data is encrypted in transit and at rest using industry-standard algorithms.
- Insecure dependencies – Assessing third-party libraries and frameworks for known security vulnerabilities.
By incorporating security vetting into the code review process, teams can prevent common security threats and improve the overall resilience of their software.
The Role of a Security-Focused Human Reviewer
While automated tools can catch a range of security vulnerabilities, human oversight is essential for ensuring a comprehensive security review. A reviewer with security expertise can:
- Identify context-specific security risks that automated tools may overlook.
- Assess business logic vulnerabilities that may not trigger traditional security scans.
- Guide security best practices to developers, fostering a culture of secure coding.
- Ensure compliance with security policies and regulatory standards relevant to the industry.
Having a dedicated security reviewer as part of the code review process ensures that security is integrated into development from the beginning, reducing the risk of vulnerabilities making it to production.
Integrating Specialized Security Tools
To strengthen security vetting, teams should incorporate specialized security tools into their code review process. These tools help automate security analysis and highlight potential risks before human reviewers enter. Common tools include:
- Static Application Security Testing (SAST) tools – Analyze source code for vulnerabilities without executing the program.
- Dynamic Application Security Testing (DAST) tools – Test running applications for security flaws.
- Dependency Scanners – Identify vulnerabilities in third-party libraries and frameworks.
- Code linters with security rules – Detect security misconfigurations and enforce secure coding practices.
While these tools significantly enhance security vetting, they should not replace human reviewers. Combining automated analysis and manual security expertise provides the best defense against vulnerabilities.
Tools for Code Reviews
No matter how you develop and implement code reviews in your organization, many tools can help - whether for automation, version history, documentation, or other purposes. There are so many options that finding the right ones can seem daunting.
Don't worry! The CTO Club’s expert reviewers have you covered. Here are four lists to get you started:
- 20 Best Code Review Tools For Developers
- 20 Best Code Analysis Tools
- The 23 Best Static Code Analysis Tools For Java
- 24 Best Source Code Management Software To Boost Your Code Game
Code Review Checklist
A code review checklist is a structured guide that ensures consistency, thoroughness, and adherence to coding best practices during the review process. By following a checklist, teams can systematically evaluate different aspects of the code, reducing the likelihood of defects, improving maintainability, and enhancing security.
A well-defined checklist helps streamline the review process and provides a standardized approach to assessing code quality before it is merged into the codebase.
Key Checklist Items for Code Reviews
A comprehensive code review checklist should cover essential areas such as readability, security, test coverage, maintainability, and performance. Below are some critical aspects to include:
Readability and Maintainability
- Is the code easy to understand and well-documented?
- Are function and variable names meaningful and descriptive?
- Is the code free from unnecessary comments or redundant code?
- Does the code follow the established style guide and formatting standards?
- Is the logic structured in a way that is easy to follow?
Security Considerations
- Does the code expose the system to security vulnerabilities such as SQL injection or cross-site scripting (XSS)?
- Are authentication and authorization mechanisms implemented correctly?
- Are sensitive credentials (e.g., API keys, passwords) stored securely and not hardcoded?
- Are proper encryption techniques used for storing and transmitting sensitive data?
- Is error handling implemented in a way that does not leak system details?
Test Coverage and Code Reliability
- Are unit tests included for new features or changes?
- Do tests cover edge cases and possible failure scenarios?
- Are integration and functional tests in place where needed?
- Does the code handle unexpected inputs gracefully?
- Have automated tests passed successfully before the review?
Performance and Optimization
- Is the code optimized for efficiency without unnecessary complexity?
- Are there any potential memory leaks or performance bottlenecks?
- Are database queries optimized to avoid unnecessary load?
- Are loops and recursive functions used appropriately to prevent excessive computation?
Reusability and Scalability
- Does the code follow principles such as modularization and encapsulation?
- Are reusable functions, components, or services used where applicable?
- Does the code introduce unnecessary dependencies that could affect scalability?
- Are API calls and data handling optimized for future growth?
How to Implement a Code Review Checklist
Using a checklist effectively requires integration into the development workflow. Here are some practical ways to implement and use a code review checklist:
- Embed the checklist in pull request templates to ensure that each pull request includes a checklist developers must complete before submission.
- Use automated tools to verify checklist items, such as static code analysis and linters, to help enforce style guides and identify security issues automatically.
- Encourage peer accountability by assigning reviewers to verify that all checklist items are addressed before approving code.
- Continuously refine the checklist as the team evolves, updating it to reflect new best practices, technology changes, and lessons learned from past reviews.
- Provide training on checklist use to ensure that all developers understand the importance of each checklist item and how to evaluate code accordingly.
By integrating a code review checklist into the workflow, teams can enforce high-quality coding practices, minimize defects, and ensure that security, performance, and maintainability are consistently addressed.
Need expert help selecting the right tool?
With one-on-one help, we guide you to your top software options. Narrow down your software search & make a confident choice.
Final Thoughts
Done well, regular code reviews are a vital part of software cultures built on collaboration and continuous improvement.
"Code reviews are not just a mechanism for improving code quality; they are an opportunity to build a collaborative, growth-oriented culture. By embracing detailed, thoughtful feedback and celebrating successes, teams can transform code reviews into a cornerstone of innovation and teamwork," posits Stone.
Subscribe to The CTO Club's newsletter for the latest insights from top thinkers in the software industry.
