Google retired First Input Delay on 2024-03-12 in favor of INP. Sentry preserves the FID signal where CrUX still surfaces it and shadows it with the modern INP score - so the year-over-year interactivity story in your dashboard doesn't break the moment Google removes the metric upstream.
Continuous monitoring of the modern signal that replaced First Input Delay. CrUX dropped FID in 2024 - INP is the surviving interactivity metric Google tracks and ranks against. Sentry confirms the replacement metric is healthy so historical FID-based dashboards stay meaningful.
CrUX 28-day p75 INP on mobile under Google's 200ms 'Good' threshold. INP is the metric Google substituted for FID on 2024-03-12. A healthy INP means the page would have passed FID too - and is what ranking systems now reference.
Lighthouse Total Blocking Time on mobile under 200ms. Where CrUX field interactivity data is sparse (low-traffic pages), TBT is the deterministic lab proxy that catches the same first-input regressions FID surfaced.
Lighthouse mainthread-work-breakdown total under 3 seconds. The condition that produced bad FID scores - early-page main-thread saturation - is the same condition that produces bad TBT and INP today. Healthy main-thread work keeps all three clean.
Paste your homepage URL. Sentry pulls 28-day CrUX INP (the modern successor), Lighthouse TBT, and main-thread-breakdown - the three signals that together explain why a page would have passed or failed FID. No signup, instant results, always free.
Sentry fetches your site, runs every FID rule, and renders the full result page before your next sip of coffee.
Each failed rule ships with a prescription paragraph. Hand it to engineering and the gap is closed before lunch.
Add your site to the daily Sentry sweep with one click. New regressions get caught the next morning.
3 rules in the FID Sentry. Daily 3:30 AM ET sweep.
One brain. Thirty-six pairs of eyes. Sentries monitor every visibility signal that decides whether search engines, AI engines, and ad platforms show you. Cortex reads what they see, weighs it against a unified corpus of platform documentation, and acts. Every move follows a defined decision protocol: action stated, reason given, impact named.