You're Invited:Meet the Socket Team at BlackHat and DEF CON in Las Vegas, Aug 7-8.RSVP
Sign inDemoInstall

← Back to Glossary


Yarn (Package Manager)

Introduction to Yarn#

Yarn is a robust, fast, and reliable package manager for JavaScript. Created by Facebook, Google, Exponent, and Tilde, Yarn was launched to address some of the challenges developers experienced with npm (Node Package Manager), the default package manager for Node.js. Yarn has quickly become popular within the JavaScript community due to its speed, security, and reliability.

Package managers like Yarn are crucial tools in modern development. They allow developers to easily add, update, or remove dependencies, which are external packages of code that your project relies on. They also ensure that these dependencies are properly versioned and installed in the correct order, reducing "dependency hell" – a common problem in development where different projects require different versions of the same package.

Yarn does this while also providing a performance boost. It achieves this speed increase through a process known as parallelization, where multiple tasks are executed concurrently. This greatly improves the installation speed of packages. Yarn also uses a cache mechanism that avoids the need to re-download packages, further increasing the speed.

Why Choose Yarn?#

When Yarn was introduced in 2016, it brought some compelling advantages over npm, some of which still hold:

  • Speed and Performance: Yarn shines in terms of speed and performance. It efficiently queues up tasks and executes them in parallel, providing a significant speed boost. Additionally, Yarn caches every package it downloads, allowing it to reuse them. If a package is cached, Yarn doesn't need to re-download it, saving time and bandwidth.
  • Workspaces: Yarn introduced the concept of workspaces, allowing developers to organize their project code into sub-packages within a single parent package. This makes it easier to manage and link dependencies across multiple projects.
  • Security: Yarn uses checksums to verify the integrity of every installed package before its code is executed. This prevents malicious or altered code from entering your project.
  • Offline Mode: Yarn's ability to work offline using its cache is a game-changer, especially for developers with unstable internet connections. This means once a package is downloaded, it's available for reinstallation without an internet connection.

How Yarn Works#

Yarn manages your project's dependencies in a simple and structured way. When you add a dependency using Yarn, it adds the details to a yarn.lock file and package.json file. The yarn.lock file ensures that the same dependencies are installed across every environment, leading to consistency across development, staging, and production environments.

Yarn install is the command that you'll run to install the dependencies from your package.json file. During this process, Yarn checks whether the packages are already in its global cache. If they are, Yarn copies them from the cache instead of downloading them from the network, speeding up the installation process.

In terms of dependency management, Yarn takes a flat approach. It installs all dependencies at the root level, ensuring a single version of a package is installed for all of your projects. This approach reduces the duplication of packages, thus saving disk space and avoiding version conflicts.

Yarn and Socket: Enhancing Your Security Posture#

While Yarn does have inbuilt features to ensure security, such as checksums, it is not foolproof against all potential threats. Here is where Socket complements Yarn, especially when it comes to supply chain attacks.

Socket proactively detects indicators of compromised packages, potentially harmful package updates, and more by monitoring changes to package.json in real-time. If a developer attempts to add a compromised package to package.json through Yarn, Socket would identify this threat, allowing the developer to mitigate the risk before it impacts the project.

As part of its deep package inspection, Socket analyzes the actual behavior of an open-source package. It can detect when packages use security-relevant platform capabilities, which are potential indicators of a supply chain attack. This proactive, rather than reactive, security approach makes Socket a perfect companion to Yarn.

Common Yarn Commands#

To effectively use Yarn, it's crucial to familiarize yourself with some of its commands:

  • yarn init: Initializes a new Yarn project, creating a new package.json file.
  • yarn add [package]: Adds a package as a dependency for your project.
  • yarn remove [package]: Removes a package from your project's dependencies.
  • yarn install: Installs all the dependencies of your project as specified in the package.json file.
  • yarn upgrade [package]: Upgrades a package to its latest version.

Each of these commands alters the package.json or yarn.lock files, which, when paired with Socket, allows for continuous monitoring and protection against potential security threats.

Migrating from npm to Yarn#

If you've been using npm and are considering a switch to Yarn, the transition is quite simple. Yarn understands the package.json file format used by npm. When you run yarn install for the first time in your existing project, Yarn creates a yarn.lock file and installs all the dependencies as specified in the package.json file.

Remember, switching to Yarn for its benefits doesn't mean you're completely safe from supply chain attacks. Pairing Yarn with a proactive security tool like Socket ensures that your application is safe from known and unknown threats in the dependency chain.


In conclusion, Yarn is a fast, reliable, and secure package manager that can greatly improve your JavaScript development workflow. It addresses many issues associated with npm, like speed and deterministic dependency installation, while introducing some unique features of its own.

However, despite its strengths, relying solely on Yarn for your security can leave you exposed to certain risks, especially supply chain attacks. Using Yarn in conjunction with Socket provides a more robust security framework for your projects, keeping your code safe and your mind at ease.

SocketSocket SOC 2 Logo



Stay in touch

Get open source security insights delivered straight into your inbox.

  • Terms
  • Privacy
  • Security

Made with ⚡️ by Socket Inc