On this page:

    What Are Code Review Tools? 

    Code review tools are software systems that help developers evaluate and improve the quality of code within a project. They automate repetitive tasks, such as detecting syntax errors or enforcing style guidelines. 

    These tools support both manual and automated review processes, allowing teams to focus on identifying complex logic issues and architectural concerns. By using code review tools, teams can ensure code maintainability, reduce defects, and increase overall code reliability.

    Code review tools integrate with development workflows, making it easier for teams to incorporate code reviews into their agile processes. They provide features like inline commenting, which enables developers to leave detailed feedback directly on the code.

    In this article:

    Advantages of Code Review 

    Developers perform code reviews for several reasons.

    Identifying Bugs and Errors Early

    Early bug identification allows teams to fix issues before they escalate. During code reviews, peers can identify potential bugs, logical errors, or security vulnerabilities that may be missed during initial development. This proactive approach is cost-effective, as bugs detected later in the development lifecycle typically require more resources to fix.

    Onboarding

    Onboarding new developers is more efficient with structured code review practices. By involving newcomers in code discussions, they gain first hand exposure to code standards and project-specific practices, speeding up acclimatization. Reviews provide a platform for newcomers to seek clarification on complex segments, supporting a deeper learning experience.

    Consistent Feedback

    Consistent feedback from code reviews ensures that all team members align with the project’s quality standards and coding conventions. Such feedback provides developers with insights into potential improvements and alternative, more efficient coding techniques. This feedback loop improves individual skills and raises the overall quality of the work produced by the team.

    Enforcing Coding Standards

    Enforcing coding standards is crucial in maintaining a consistent and readable codebase, and code review tools aid in this process. These tools can automatically check if new code adheres to predefined style guides and standards, catching common issues before they reach production. This ensures that every piece of code follows the same guidelines and makes maintenance easier.

    Reduced Technical Debt

    Code reviews aid in reducing technical debt by identifying suboptimal code constructs and recommending improvements proactively. When developers receive immediate feedback on poor coding practices, it addresses issues before they solidify as deep-seated problems in the codebase. This early intervention prevents long-term complications. 

    Key Features of Code Review Tools

    Code review tools typically include the following capabilities.

    Inline Commenting

    Inline commenting is a way for reviewers to provide feedback directly on the code. It allows for comments to be attached to specific lines or sections, enabling precise communication and reducing ambiguities often associated with general reviews. This is especially beneficial for distributed teams, where direct communication isn’t always feasible.

    Version Control System

    Integration with version control systems (VCS) provides a framework for tracking changes and managing code history. VCS integration enables developers to submit pull requests or changes for review easily, maintaining a record of all modifications associated with a project. This history is crucial for auditing and understanding the evolution of the codebase.

    Automated Checks and CI/CD Integration

    Automated checks within code review tools perform preliminary reviews of the code, checking for compliance with coding standards and identifying potential performance issues. These checks are integrated into CI/CD pipelines, automatically validating code changes before they are merged into the main branch. 

    Diff Visualization

    Diff visualization enables reviewers to see changes between different versions of the code clearly. This visual representation highlights the additions, deletions, and modifications in the code, allowing reviewers to focus on what has changed and why. Such clarity is useful for efficient reviews, as it allows team members to quickly identify areas of concern.

    Approval and Merge Management

    Approval and merge management features support a smooth transition from review to integration. They allow reviewers to approve changes, ensuring they meet the required quality standards before being integrated into the main codebase. Automated merge functionality often follows approval, reducing manual intervention and minimizing the risk of human error during the merging process.

    Branch and Pull Request Management

    Branch and pull request management aid in organizing and coordinating development efforts across teams. These features support the creation and tracking of branches for different features or bug fixes, allowing teams to isolate work. Pull requests support discussions around specific changes, ensuring that code is reviewed and tested independently before integration into the main codebase.

    Tips from the expert

    Omer Rosenbaum
    Omer Rosenbaum
    CTO & Co-founder at Swimm
    In my experience, here are tips that can help you better leverage code review tools:
    1.
    Automate security and code quality checks early: Integrate static analysis and security tools (like Codacy or CodeScene) to run automatic checks on every pull request. This ensures that potential vulnerabilities and coding issues are flagged early, reducing the burden on manual reviewers and improving code quality.
    2.
    Implement context-aware reviews: Tools like CodeStream provide real-time telemetry and error insights during the review. Use this functionality to see how code changes affect performance in production, making your reviews more data-driven rather than purely syntax-focused.
    3.
    Enforce quality gates: Set up code quality gates (available in Gerrit, Codacy, and CodeScene) that prevent merging code unless it meets predefined thresholds, such as test coverage, code complexity, or security issues. This enforces best practices consistently across teams.

    Notable Code Review Tools 

    1. Swimm


    Swimm is a code review tool that enhances the review process by providing live, context-aware documentation directly linked to the code. It helps reviewers understand the changes being made and the broader codebase, making reviews faster, more effective, and collaborative.

    Key features:

    • Contextual documentation in reviews: Automatically surfaces relevant documentation for any code changes, ensuring that reviewers have the context they need without leaving the review environment.
    • Live documentation updates: Keeps documentation aligned with code changes, so reviews are always based on the most current information, reducing misunderstandings and rework.
    • Guided code walkthroughs: Allows teams to create step-by-step walkthroughs for complex code areas, enabling reviewers to grasp architectural patterns and logic more quickly.
    • Knowledge-sharing integration: Captures insights and discussions from code reviews, turning them into shared documentation that benefits the entire team.
    • Improved review efficiency: With clear documentation and context, reviewers can focus on code quality and functionality, reducing review time and enhancing collaboration.

    2. GitHub

    GitHub offers a suite of lightweight code review tools integrated into its platform, simplifying the review process within pull requests. These tools allow teams to evolve projects, propose new features, and refine changes before updating the source code.

    Below are the key features of GitHub’s code review system:

    • Pull requests: Handles feature changes and improvements, allowing teams to coordinate feedback and implementation before updating the codebase.
    • Diffs: Offers side-by-side diffs to highlight added, deleted, or modified code, making it easier to track changes and understand updates.
    • Commit history: Lets users browse through commits and comments in a timeline format to view the evolution of a pull request and see what’s changed since the last check.
    • Blame view: Tracks changes in a file over time, providing a detailed look at how the file has evolved.
    • Inline comments: Lets users leave comments directly on lines of code to clarify suggestions and discuss syntax or structure.

    Source: GitHub 

    3. RhodeCode

    RhodeCode is an enterprise-grade, open-source source code management platform that unifies git, Mercurial, and subversion under a single interface. Its code review tools enable teams to collaborate more effectively, improve code quality, and maintain security. 

    License: AGPLv3 

    Repo: https://rhodecode.com/open-source

    Below are the key features of RhodeCode’s code review system:

    • Unified code reviews: Conducts code reviews across git, Mercurial, and subversion repositories with a consistent workflow, allowing teams to provide feedback and iterate on code regardless of the version control system.
    • Inline commenting: Offers detailed feedback directly on lines of code, enabling clear and effective communication for refining code quality.
    • Smart commits: Triggers code review approvals and automates workflows by using smart commits, which enhance the review process by linking commits with related tasks or approvals.
    • Workflow automation: Integrates issue trackers and automates workflows to expedite code reviews, ensuring that the review process is both efficient and scalable.
    • Permission management: Manages repository access with enterprise-level controls, ensuring that sensitive code is protected while maintaining granular permissions for different team members.

    Source: RhodeCode 

    4. Codacy

    Codacy is a combined code quality and security platform that helps developers and teams maintain clean, secure code. It integrates with development workflows, offering automated code reviews and tools to identify and fix issues efficiently. 

    Below are the key features of Codacy’s code review system:

    • Automated code reviews: Automatically analyzes every pull request to monitor and enforce coding standards, ensuring consistent code quality across projects.
    • Security checks: Offers support for static application security testing (SAST), software composition analysis (SCA), and secrets detection. Identifies and helps resolve potential security vulnerabilities within the code.
    • Inline feedback: Lets users provide direct feedback on code changes with inline comments, allowing for clear communication and quicker resolution of issues.
    • Test coverage monitoring: Helps track and enforce test coverage on each pull request to ensure that changes do not introduce breaking issues.
    • AI-powered fixes: Suggests AI-driven code fixes that developers can apply directly in their git workflows, speeding up the process of resolving code quality issues.

    Source: Codacy 

    5. Crucible

    Crucible is a collaborative code review platform that helps teams review, discuss, and improve code quality across multiple version control systems. Supporting git, SVN, Mercurial, CVS, and Perforce, Crucible enables formal and lightweight code reviews, making it easier for development teams to identify defects and share knowledge. 

    Below are the key features of Crucible’s code review system:

    • Flexible code reviews: Users can create formal, workflow-based, or quick reviews, assigning team members as reviewers to ensure thorough examination of code changes.
    • Threaded discussions: Supports threaded discussions within code reviews, allowing users to comment on specific lines, files, or entire changesets.
    • Unified activity tracking: Helps track commits, reviews, and comments through a unified interface, allowing developers to prioritize.
    • Review reporting: Offers insights into code coverage and review status, identifying areas of the codebase that haven’t been sufficiently reviewed and any blockers to progress.
    • Audit and compliance: Offers detailed audit trails for every code review, making it easy to maintain compliance with internal or external standards.

    Source: Crucible 

    6. Axolo

    Axolo simplifies code reviews by integrating pull request (PR) channels directly into Slack, enabling teams to collaborate more efficiently and reduce delays. By creating ephemeral Slack channels for each pull request, Axolo centralizes discussions, automates reminders, and ensures timely reviews, minimizing the time to merge. 

    Below are the key features of Axolo’s code review system:

    • Pull request channels: Automatically generates dedicated Slack channels for each PR, centralizing conversations and ensuring all feedback is tracked in one place.
    • Automated PR reminders: Sends daily reminders for stale pull requests, helping ensure that reviews happen promptly and avoiding unnecessary delays in the merge process.
    • CI/CD and GitHub Actions integration: Sends updates about branch conflicts, pull request checks, and deployment statuses directly in Slack channels.
    • Customizable notifications: Allows users to customize notifications and set time slots for code reviews, ensuring that developers stay focused on their work.
    • PR recap for stand-ups: Offers daily pull request recaps to keep the team accountable and in sync during stand-ups, providing a quick overview of the review status and pending actions.

    Source: Axolo 

    7. Review Board

    Review Board is a code review platform that goes beyond traditional pull request workflows, allowing teams to review not only code but also documents, images, and other assets. It supports a wide range of source code management systems and offers customization and automation capabilities. 

    License: MIT

    Repo: https://github.com/reviewboard/reviewboard

    GitHub stars: 1k+

    Contributors: 200+

    Below are the key features of Review Board’s code review system:

    • Flexible code reviews: Lets users create and manage review requests for code changes, documents, and images across multiple source code management systems such as git, Mercurial, subversion, and Perforce.
    • Code review features: Enables multi-line commenting, moved code detection, and smart indentation-aware line changes, with the ability to comment on any line of code, even outside the diff.
    • Image and document review: Helps review and compare images, mockups, and PDFs with features like side-by-side diffs, contextual commenting, and transparent overlay comparisons.
    • Issue tracking and discussion: Each review includes threaded discussions where reviewers can comment on specific sections of code, images, or documents. 
    • Dashboard for review management: Helps keep track of review requests with a customizable dashboard that provides an overview of reviews awaiting action.
    • Automated reviews: Integrates with CI systems like Jenkins, CircleCI, and Travis-Cl, and supports automatic code reviews to detect issues early in the development process.

    Source: Review Board

    8. CodeStream

    CodeStream integrates performance telemetry and error tracking directly into the IDE, simplifying code reviews by providing real-time insights into code-level performance and errors. It enables developers to quickly identify and remediate issues without switching context. 

    License: 

    Repo: https://github.com/TeamCodeStream/codestream-server

    GitHub stars: 50+

    Contributors: ~20

    Below are the key features of CodeStream’s code review system:

    • In-IDE telemetry integration: Shows relevant performance metrics and production telemetry alongside the code within the IDE, giving context for code reviews.
    • Error discovery and debugging: Discovers recent production errors related to the code and walks through the stack trace in the IDE.
    • Code-level performance monitoring: Sends notifications of poorly performing code since the last release and helps quickly identify underperforming methods.
    • Log search without context switching: Users can search logs from services like New Relic APM, infrastructure agents, or OpenTelemetry directly from their IDE.
    • Service performance monitoring: Monitors how services built from the code are performing in different environment, with insights into errors, vulnerabilities, and SLO compliance.

    Source: New Relic

    9. CodeScene

    CodeScene is a code analysis and visualization tool that elevates code reviews by providing insights into code quality, technical debt, and team dynamics. By analyzing behavioral factors and code evolution, it helps engineering teams make informed decisions, improving code and delivery performance. 

    Below are the key features of CodeScene’s code review system:

    • Automated code reviews: Automates code reviews and sets quality gates for pull requests, ensuring that code meets predefined quality standards before being merged.
    • Code health metrics: Provides insights into code health by file, team, and author. The Code Health metric considers 25+ factors, offering actionable recommendations for prioritizing refactoring efforts and improving code quality.
    • Prioritize refactoring: Provides insights to identify high-risk areas in the codebase, enabling teams to prioritize refactoring targets.
    • Team dynamics insights: Offers personalized dashboards that offer insights into team performance, knowledge ownership, and the effects of staff changes. 
    • Software delivery metrics: Tracks system-level costs of planned versus unplanned work and analyze delivery speed and frequency. 

    Source: CodeScene 

    10. Gerrit

    Gerrit is a web-based code review tool built on top of Git version control, designed to simplify the review process by providing a central repository for code changes and discussions. It allows teams to review, comment, and approve code before it is merged into the codebase. Gerrit is suitable for both open source projects with restricted approvers and trusted team environments. 

    License: Apache-2.0 

    Repo: https://github.com/GerritCodeReview/gerrit

    GitHub stars: ~1k

    Contributors: 300+

    Below are the key features of Gerrit’s code review system:

    • Centralized code reviews: Serves as the authoritative repository where all code changes are submitted to a store of Pending Changes, awaiting review and approval before being merged into the main codebase.
    • Pending changes management: Code changes are placed in a queue for review, where reviewers can inspect, discuss, and suggest improvements. Only after approval from the required number of reviewers is the change integrated into the project.
    • Commenting and discussion: Reviewers can leave detailed comments and feedback on specific code changes, capturing the conversation around each modification. 
    • Change history tracking: Maintains a complete history of every change, including who made the change, what was modified, and why. 
    • Access control: Offers fine-grained access controls, allowing teams to customize permissions for contributors and reviewers. This is particularly useful in open source projects or large teams.

    Source: Gerrit

    Related content: Read our guide to code review best practices

    Conclusion 

    Code review tools play a critical role in modern software development, helping teams maintain high-quality codebases through continuous feedback and collaboration. These tools assist in the review process by automating repetitive tasks, integrating with version control systems, and providing features such as inline commenting and automated checks. By incorporating code reviews into the development workflow, teams can catch issues early and enforce coding standards.