INP Debugger & Interaction Analyzer

Lab tools traditionally only measure page load metrics like LCP and CLS without actually interacting with buttons, dropdowns, or navigation menus. INP Debugger bridges this gap by automatically discovering clickable and interactive components across the page and dispatching realistic pointer events and keystrokes.

Each interaction is benchmarked under simulated mobile CPU throttling and network constraints, revealing responsiveness bottlenecks that desktop development environments frequently mask.

When an interaction feels sluggish, the cause could be a congested main thread waiting to start the handler, an expensive JavaScript callback, or an intense layout recalculation. INP Debugger isolates each phase into Input Delay, Processing Time, and Presentation Delay.

With clear visual breakdown bars and millisecond measurements, you immediately know whether to focus on breaking up long tasks, refactoring callback logic, or optimizing DOM rendering.

Leveraging Chrome's Long Animation Frames API, INP Debugger attributes slow interactions directly to the JavaScript files, function names, and invoker types that occupied the main thread during the interaction window.

Combined with real-world 28-day Chrome User Experience Report (CrUX) field data, you can verify both what real visitors experience in the field and the exact code blocks causing responsiveness regressions.