8 Free/Open Source Code Review Tools for 2023

Code review is a crucial part of the development process. With code review, you can detect errors early in development. 

The code review tool automates the entire process of reviewing the application development process. So, it has become a crucially important tool for the development team in recent times and helps organizations gain a significant competitive advantage.

With the code review process, you can improve the software quality. To help you, we have listed the top eight free and open-source code review tools.

What is the Code Review Process?

The code review process is the orderly testing of software to find and remove errors, bugs, buffer overflows, and other vulnerabilities found in the codes.

These code review processes are methodically documented and follow severe defect detection techniques from peers and technical experts.

There are four, sometimes five, participants involved in code creation and inspection – the author, the moderator, the reviewer, the reader, and sometimes an observant.

The code reviews are led by trained moderators and reviewers who are NOT the author of the coded program, and these reviews are performed without any management participation.

Since it is a quality assurance activity, reviewers scrutinize the codes written by the authors and prepare a report with a list of findings to be fixed.

Why is Code Review Necessary?

The code review process is necessary because it is not formally established in the schools’ curriculum. The code review is a process that evolves with an organization’s age. Learning about the nuances of project management and programming language is comparatively easier. The code review process is crucial for the following reasons: 

1. It minimizes your chances of having critical issues. 
2. It improves and increases the new code efficiencies. 
3. It makes sure there are no disturbances in the code.
4. It ensures that the new code adheres to the guidelines.
5. It improves team members’ expertise.

How to Perform a Code Review?

There are many processes and techniques to perform a code review which usually involves a lot of meetings between the distinct roles mentioned above. 

Heavyweight inspection processes go up to 6-7 steps involving everyone working only when the code review comes on their plate. Lightweight inspection processes affect everyone to work simultaneously with each other.

Not many follow heavyweight inspection processes anymore, which means lightweight processes are trending more with the increase in the development of software applications across the globe.

Here are a few lightweight inspection techniques:

1. Over-the-shoulder Reviews

This code review process is the most informal and common. Over-the-shoulder means that a reviewer hovers over the author while the author displays the changes made in the code at their coding workstation.

The author is the person that leads the code review by sitting at their computer, explaining the changes they made in the code while going through multiple tools and files in the project.

If the reviewer finds any discrepancy, they engage on the spot with the author (this engagement is called pair programming) to fix the missed issues. If the changes are too significant, the live code is offline.

However, with modern desktop-sharing tools, this “over-the-shoulder” review has become remote and easy to implement over long distances.

2. Email pass-around Reviews

This code review process is prevalent and preferred by most open-source projects. Here, the entire file or changes in the code are packed up by the author and sent to the reviewers through email. Reviewers then examine the code data and ask relevant doubts and queries in the same thread to the authors.

In this method, it is easier to involve other developers through email to ask for suggestions, changes in the code, expert advice, or even complete deferral.

3. Pair programming Reviews

People generally associate this code review technique with Extreme Programming (XP) because it incorporates a continuous code analysis. However, in pair programming, two developers produce code from a single workstation, with only one authoring the code and the other person freely discussing any changes and suggestions needed as a reviewing developer.

Pair programming has shown to be very useful in finding bugs as well as promoting knowledge transfer. 

However, this process poses a controversial issue about whether it is better or worse or equivalent to more standard reviewing methods because the reviewing developer is continually being a critique polishing the code. 

At the same time, the author might get frustrated and lose their chain of programming the code every time between writing and listening for suggestions.

4. Tool-assisted Reviews

A code review done with the help of specialized tools that helps in processes like collecting files, commentary, transfer, displaying data, collecting metrics, etc., is called a tool-assisted review.

Tool-assisted reviews allow product managers and administrators to exercise some control over the workflow. This review process is mostly preferred in commercial software, open-source projects, or home-grown scripts.

Either way, it requires a lot of money to be invested in specialized tools to create a better code review environment.

These code review processes help improve the quality of the software. To help you, we have listed the top eight free and open-source code review tools that you can look at.

Why Should You Use Open Source Code Review Tools?

Source: Vervelogic

Efficiency and effectiveness are the most important reasons to use a code review tool. The code review process helps the reviewer focus solely on the code. It consolidates with the development cycle and initiates a code review before a new code is mixed with the primary codebase. You can get a tool that is adaptable to your technology stack and seamlessly integrates with the workflow. 

In the software development process, you have two types of code testing trends: 

1. Dynamic

With dynamic analysis, you can check whether a code follows the rules and runs unit tests performed by a predefined script.

2. Static

With static code analysis, a developer can create a new code that can be merged into the current code.

Best Free and Open Source Code Review Tools to Consider

1. Codebrag

Codebrag is one of the best open source code review tools that are quite simple to use. It is mainly used to review inline comments and likes, smart email notifications, non-blocking codes, and more. 

It is a lightweight code review tool open source that makes the whole process of review entertaining and structured. Furthermore, it offers an agile code review that helps deliver a high-quality application. 

Features

• Lets you easily track your tasks with a simple to‑do list
• Offers full IDE integration and also allows it to be installed locally
• Easily manages all comments and commits in one place

Pricing

• Please connect with the vendor for pricing.

Pros and Cons

2. Gerrit

Gerrit is among the free and open source code review tools that help to review code on a web browser. It is a code review tool that is self-hosted and lightweight. With Gerrit, you can enable every committer involved in a project to keep track of all the changes. 

The biggest advantage is that it is among the free code review tools that review the changes before accepting the codebase. Besides, the change facilitator opens conversations about the changes by leaving comments and notes. 

Features

• Can be integrated with Git — a distributed Version Control System
• Can use it to discuss a few detailed segments of the code
• Offers repository management for Git

Pricing

Please connect with the vendor for pricing

Pros and Cons

3. Reviewable

Reviewable is one of the best open source code review tools in terms of functionality and appearance. It is among the open source secure code review tools that offer a clean and interactive UI that enables it to perform advanced functionality easily. For example, you can perform actions like comparing the differences between any two file revisions or installing customizable logic that lets you know if the code review is complete. 

Features

• Enables seamless integration and minimal admin work
• Improves the code quality by highlighting the syntax
• Lets you map line comments across file revisions and stay in place until it is resolved

Pricing

• The pricing starts at $39/month

Pros and Cons

4. ReviewBoard

ReviewBoard is among the simple yet powerful free code review tools that make the entire review process meticulous. In addition, it provides functionalities like differences and the ability to make comments. 

Besides, it is relatively easy and quick to learn. It also provides a clean interface. ReviewBoard is the best option for developers looking for a no-frills code review. It has 1.2K GitHub stars and 369 GitHub forks.

Features

• Provides syntax highlight that makes it highly readable
• Supports pre-commit and post-commit reviews
• Seamlessly integrates with ClearCase, CVS, Perforce, Plastic, and more.

Pricing

• The pricing starts at $12/user/month

Pros and Cons

5. Phabricator Differential (Open Source)

Phabricator Differential is among the source code review tools free that lets you download and install it on your hardware or launch a hosted instance with them. It is considered the best code review tool amongst the top open source code review tools. 

What’s more, you can use HG, Git, and SVN. And if it isn’t enough, this code review tool open source allows easy team discussion, planning, testing, and coding. The plus point is that it is scalable to multiple servers. 

Features

• Enables developers to leave comments and notes
• Allows you to publish all repositories to mirrors
• Easily host the repository locally

Pricing

• The pricing starts at $20/month

Pros and Cons

6. Rhodecode

Rhodecode is a popular open-source code review tool that makes it easy to handle code management. It is a well-protected enterprise source code management system that is an integrated tool for Mercurial, Git, and Subversion. 

It offers two editions. The first one is licensed per user, Enterprise Edition, and the other is Community Edition, a free and open-source version. 

Features

• Automates the workflow for faster collaboration
• Allows for team collaboration for better code quality check
• Enables you to integrate with the existing code base with new issue tracker tools

Pros and Cons

7. CodeStriker

CodeStriker is among the top open source code review tools. It supports reviews of formal documents and differences generated by SCM and plain unified patches. In addition, there is a plug-in architecture for issues-tracking systems.

Moreover, this code review tool open source minimizes paperwork and provides a clean interface for code inspections.

Features

• It can be easily integrated with Bugzilla, CVS, ClearCase, etc.
• Enables you to record code inspection metrics as a part of the process
• Runs on all of the important platforms and browsers

Pricing

• Please connect with the vendor for pricing details.

Pros and Cons

8. SmartBear

SmartBear has automated software, Collaborator, to instantly help you with your code quality. In addition, it supports most version control systems like Subversion, CVS, TFS, Perforce, and Git. 

This Smartbear software allows reporting and analyzing key metrics and reviewing design documents related to your code review process. With SmartBear, you can reduce your rework and get answers quickly.

Features

• Track and manage defects
• Build custom review templates
• Collaborate on documents and software artifacts
• Improve processes with reporting

Pricing

• The pricing for a team starts at $715/year.

Pros and Cons

Conclusion

So, these were the top 8 open source code review tools from us, which developers mostly use all across the globe.