Web Performance Calendar » Build Your Own Site Speed Testing Tool with Puppeteer

Site performance plays a crucial role in delivering a seamless user experience. Slow load times, unexpected layout shifts, and unresponsive interactions can negatively impact both SEO and user satisfaction. However, identifying these issues under real-world conditions requires the right tools. This is where Puppeteer comes in. Puppeteer is a Node.js library that allows developers and technical SEOs to automate headless Chrome browsers. A headless browser refers to a web browser that runs without the usual interface. In this case, the browser is run through your command line. It enables you to simulate real user environments—including different network speeds, devices, and CPU capabilities—and measure key performance metrics such as Largest Contentful Paint (LCP), Cumulative Layout Shift (CLS), and Interaction to Next Paint (INP).