Capability
Core Web Vitals monitoring: what a crossed LCP actually costs in ranking.
A Core Web Vitals regression is the kind of failure that reads as silent for two weeks, then a sudden ranking drop the third. Core Web Vitals monitoring is the daily probe that names the URL, the metric (LCP, CLS, INP), and the day the regression crossed the threshold — before the ranking drop.
- Daily probes of LCP (Largest Contentful Paint), CLS (Cumulative Layout Shift), and INP (Interaction to Next Paint).
- Email cadence the day a metric crosses its threshold for two consecutive days.
- Names the URL, the metric, the value, and the threshold in every alert.
- Catches the LCP regression that a Lighthouse-on-demand run would miss between audits.
- No agent on your server. The probe runs from the outside, like a visitor.
How it works
Setup, in three beats.
Step 01
Add the URLs a visitor types first — landing, product, home
Paste the URLs that matter for ranking: the home page, the landing page, the product detail, the blog index. Set a threshold per metric if you want stricter or looser bounds than the default. SiteGuardian starts probing the next minute.
Step 02
Let the daily probe find the next LCP regression
Most LCP regressions come from a four-step chain: a hero image gets larger, a font swaps late, a third-party script lands heavier, a CDN region serves slow. Probes that happen daily catch the change within 24 hours; the email cadence fires on the second day of the threshold trip.
Step 03
Catch the metric regression before the next ranking change
A Core Web Vitals regression costs ranking in two waves: the page experience signal first, then the ranking drop two to four weeks later. SiteGuardian’s daily probe is the early signal — the URL, the metric, the value, the threshold. The fix is on the engineering team; the cue is in the inbox.
What the alert actually says
One email. One URL. One timestamp.
Your URL https://example.com/landing crossed LCP threshold on day 2 — 4.2s today, threshold 2.5s. The regression started on 2026-07-12, two days after the hero-image swap.Frequently asked
The core web vitals monitoring questions, answered flat.
Frequently asked
Related reading
Keep exploring.
Try it
Start monitoring my site.
Starter is $19 a month — one site, ten URLs, every-five-minute checks. Pro is $39 a month — three sites, fifty URLs, every-minute checks. Lifetime is $299 paid once and stays yours with every future update included.
Stay updated
Want us to email you when we ship a feature for this use case?