CLS layout shift debugger

Each shift's score is the browser's own impact fraction times distance fraction, so the numbers here are the numbers Chrome recorded, not a re-computation. Session windows follow the Layout Instability spec: a shift joins the running window when it starts less than 1 s after the previous shift and less than 5 s after the window's first shift, and CLS is the largest window sum. Shifts within 500 ms of a click or keypress are excluded, as the metric excludes them. What this tool does not do: it does not watch a live page, it does not see your real visitors' field data, and its likely causes are heuristics over selectors and rect deltas, good for suspect lists, silent on anything a selector cannot say, such as whether an image really lacked width and height.