Simple Performance Bar is a browser add-on developed by Oliver Tse. Designed for Chrome, this free tool provides users with a simple and convenient way to monitor the performance of websites they visit.

Using the Navigation Timing API, Simple Performance Bar presents network, server, client, and page load times as a group of easy-to-read bars fixed to the bottom of the browser window. With each page load, the performance bar automatically appears, allowing users to quickly assess the site's performance.

The calculations for network, server, and client times are based on the W3C Navigation Timing Draft. Network time is determined by subtracting the navigation start time from the connection end time. Server time is calculated by subtracting the connection end time from the response end time. Lastly, client time is measured by subtracting the response end time from the load event end time.

Simple Performance Bar is a valuable tool for anyone interested in monitoring and optimizing website performance. Its user-friendly interface and accurate performance measurements make it a useful addition to any Chrome user's browsing experience.