CrUX Tracker — Know When Your Core Web Vitals Slip Before It's Too Late

LCP · INP · CLS

the three metrics Google ranks on, from real Chrome users

6 mo

of trend history in every report, mobile and desktop split

100%

field data — no lab guesses, no synthetic tests

likely cause attached to every regression alert

Lab vs field

A perfect Lighthouse score can still fail Core Web Vitals

Lab tests run on a simulated device with a clean cache — they aren't what Google ranks on. Field data from real Chrome users is. A site can score 95 in Lighthouse and still fail LCP for actual visitors on mid-range phones and patchy networks. That gap is exactly what CrUX Tracker watches: the real-user numbers, month over month, with alerts the moment a metric regresses.

Sample Report

Every alert comes with the likely cause — not just the number.

A fictitious retail brand, monitored the way your sites would be. Open the full sample in the tool.

StyleMart India — June 2026 Field Data Sample Data

LCP · Mobile

2.1s

Good

INP · Mobile

289ms

Needs Improvement

CLS · Mobile

0.02

Good

INP regressed 41ms vs May — likely cause identified

Third-party chat widget now loads synchronously on product pages. Defer or lazy-init to recover interaction latency.

Open the full sample report →

How It Works

Set up once, stay informed forever

Add your sites

Enter the domains you care about — yours, your clients', even competitors'. No tags, no code changes, no limit.

CrUX data flows in

Real-user LCP, INP, CLS, FCP and TTFB from Google's Chrome UX Report API, split by mobile and desktop.

Monthly trend reports

Six-month trend lines per metric, delivered by email — so a slow drift is caught before it becomes a ranking problem.

Alerts with the cause

When a metric regresses, the alert names the likely cause — no lazy-load, missing preload hint, no CDN on hero images — not just the number.

FAQ

Questions site owners ask us

How is this different from Lighthouse or PageSpeed Insights?

Those are lab tests — one synthetic run on simulated hardware. CrUX Tracker uses field data: the aggregated experience of real Chrome users on your actual site. Field data is what Google's ranking systems evaluate.

Where does the data come from?

Google's Chrome UX Report (CrUX) API — the public dataset of real Chrome user experiences. We fetch it monthly, store the trend, and analyse the changes.

How many sites can I track?

There's no fixed limit — add the sites you need.

What happens when a metric regresses?

You get an email alert with the metric, the size of the regression, the affected device class, and the likely cause our analysis identifies — so your developer starts with a diagnosis, not a mystery.

Can you fix the issues too?

Yes. Monitoring is self-serve; when something regresses, NDW's engineering team can take the diagnosis through to remediation. Use the form below.

From the Field Notes

Ideas behind CrUX Tracker

Recent articles from the NDW blog about the problem this tool solves.

Jun 24, 2026

Core Web Vitals in 2026: What Actually Counts as “Good”

Everyone says Core Web Vitals matter — far fewer can name the numbers you have to hit. Here are the 2026 thresholds for LCP, INP and CLS, and the rule that decides pass or fail.

Read article →

Jun 22, 2026

Your Lighthouse Score Says 95. Real Users Disagree. Here's Why.

A perfect Lighthouse run can still fail Core Web Vitals. The reason is the gap between lab tests and the real-user field data Google actually ranks on.

Read article →

Contact

A metric slipped and you need it fixed?

Tell us your site and what regressed — our engineers work from the same diagnosis the tracker gives you, so remediation starts informed, not from scratch.