Catch the release that made your pages slow

Vitals Clock measures your pages daily with the same public data Google uses, compares each result with the last seven days, and tells you when a metric slips.

Speed rarely breaks loudly

Nobody ships a release called "make the site slower". It happens in small steps. A marketing tag added on Thursday. A hero image uploaded at 4 MB. A cookie banner that shifts the layout. A new font loaded from a third server. Each one adds a few hundred milliseconds or a little layout shift, and no one notices until search traffic dips or someone runs a test for an unrelated reason.

By then, finding the cause means digging through weeks of changes.

Vitals Clock runs the test every day, keeps the numbers, and flags the day things moved.

How it works

Add your URLs. Home, top landing pages, a product page, checkout. Whatever earns you money.
We measure daily. Lighthouse lab tests on mobile and desktop through the PageSpeed Insights API, plus real-user field data from the Chrome UX Report.
You hear about regressions. When a metric crosses Google's "good" line, or worsens by more than your set percentage against the 7-day median, you get an alert with the before and after.

Two kinds of data, both shown

Lab data comes from a controlled Lighthouse test: performance score, Largest Contentful Paint, Cumulative Layout Shift and Total Blocking Time. It reacts the same day you ship a change, which makes it good for catching regressions early.

Field data comes from real Chrome users and is published in the Chrome UX Report: LCP, Interaction to Next Paint and CLS at the 75th percentile. It moves slowly because it covers a rolling 28-day window, but it is what Google uses for the page experience signals in search.

Vitals Clock keeps both side by side, so you can see a lab regression today and watch whether it shows up in field data over the following weeks.

Built to cut through noise

Lab tests vary from run to run. A single slow result is not a regression. We run three tests per check and use the median, then compare against the median of the previous seven days. Alerts fire on sustained movement, not a one-off bad run.

What you can see

Daily charts for each metric, mobile and desktop
Field data trends for each URL and the whole origin, with several months of weekly history
Page weight and request count from our own fetch, so a jump in either points you at the cause
Competitor URLs on Pro, so you know whether a dip is you or the whole sector
PDF reports on Pro, and white-label reports on Agency

Alerts

Email by default. Slack and Microsoft Teams webhooks from Starter. A generic webhook for anything else. A weekly summary lands every Monday either way.

FAQ

Is this the same data as PageSpeed Insights?

Yes. We call the PageSpeed Insights API for lab tests and the Chrome UX Report API for field data. The difference is that we run them every day, keep the history and alert you on changes.

Why does my lab score jump around?

Lighthouse runs in a simulated environment and is sensitive to server response time, third-party scripts and network variation. That is why we take the median of three runs and compare it with a seven-day median.

My page has no field data. Why?

The Chrome UX Report only publishes data for pages and origins with enough real Chrome traffic. Low-traffic pages may only have origin-level data, or none. Lab data still works for every public URL.

Do you track INP?

Yes, from field data. INP needs real user interactions, so lab tests cannot measure it directly. We show Total Blocking Time from the lab as an early hint.

Can I test pages behind a login?

No. The tests run against public URLs only.

How many checks per day?

Once a day on Free, twice on Starter and four times on Pro and Agency.

Are you part of Google?

No. Vitals Clock is independent. We use Google's public APIs.

FAQ