Client-Side Observability

Client-side observability is a crucial component of modern web applications. It enables developers to monitor and understand how their application is performing in real-time from the user's perspective. In this blog post, we will explore what client-side observability is, why it is important, and some of the best practices for implementing it.

What is Client-Side Observability?

Client-side observability refers to the ability to monitor and measure the performance of a web application on the client-side, i.e., the browser. This includes metrics such as page load times, network requests, errors, and user interactions. Client-side observability can be achieved through various tools and techniques, including browser APIs, JavaScript libraries, and third-party services.

Why is Client-Side Observability Important?

Client-side observability is essential for several reasons. First, it enables developers to identify and diagnose issues in real-time, which is critical for maintaining a high-quality user experience. Second, client-side observability can provide valuable insights into how users are interacting with an application. Finally, client-side observability can help ensure that an application is performing well across a variety of devices and browsers.

Components of Client-Side Observability

There are several kinds of data that make up a comprehensive approach to client-side observability:

  1. Analytics - Users, sessions, and activity
  2. User Experience - Performance, usability
  3. Errors - How the site is breaking
  4. API - The status and performance of APIs needed by the client
  5. Integrity - Executables and user data

Most tooling focuses on a subset of this data. One notable exception is Request Metrics, which attempts to correlate client-side observability data to find the issues that matter the most.

Best Practices for Client-Side Observability

Implementing client-side observability requires careful planning and execution. Here are some best practices to consider:

  1. Choose the Right Tools
  2. Collect Relevant Metrics
  3. Monitor in Real-Time
  4. Analyze Data
  5. Iterate and Improve

By following best practices and using the right tools and techniques, developers can gain valuable insights into how their application is performing and continuously improve it over time.


Client-side observability is a critical component of modern web applications. By monitoring and measuring performance in real-time, identifying and resolving issues quickly, and optimizing the user experience, developers can improve the overall quality of their application and ensure that it performs well across a variety of devices and browsers.