Core Web Vitals Annotations

Annotate a website with the Core Web Vitals

Core Web Vitals Annotations Chrome Extension

Core Web Vitals Annotations is a valuable tool for website owners and developers seeking to improve their site's visitor experience. This Chrome extension overlays performance metrics and elements that affect First Input Delay (FID), Largest Contentful Paint (LCP), and Cumulative Layout Shift (CLS) directly onto your website's pages. Visual annotations make it easy to identify elements that are causing layout shifts or slowing down your page load speed, allowing you to directly address these issues and improve your site's overall performance.

Extension stats

By: delambo
Rating: 3.00
(2)
Version: 0.0.2 (Last updated: 2021-02-24)
Creation date: 2021-02-23
Risk impact: Very low risk impact
Risk likelihood:
Manifest version: 2
Permissions:
  • activeTab
Size: 195.58K

Other platforms

Core Sports World (v2.19.0)
4.04 (233) 22,720+
Not available on Firefox
Not available on Edge
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Extension summary

This extension will overlay annotations onto your website to highlight page attributes that had an impact on the Core Web Vitals performance metrics, First Input Delay (FID), Largest Contentful Paint (LCP) and Cumulative Layout Shift (CLS). It also reports the Core Web Vitals metrics for the page, using Google's recommended color-coded thresholds.

Two types of annotations will be overlaid onto elements of a webpage:

  1. Elements that had layout shift and contributed to the Cumulative Layout Shift score. Depending on the severity of the shift, the annotations will be color coded from lowest impact to highest - yellow -> orange -> dark orange -> red. In the upper left hand corner of each annotation you will find the shift score.

  2. The element with the Largest Contentful Paint will be highlighted with a dashed purple annotation. It will include the paint time in the upper left hand corner of the annotation.

The extension popup should open a grid with the FID, LCP and CLS metric timings. At the bottom of the popup is a button to remove the annotations from the website.

Except for the Largest Contentful Paint, the Core Web Vitals metrics are user initiated. Take note of the following when you use the plugin and debug your website:

  • The First Input Delay is captured after a user clicks or taps a key on the webpage. If you open the extension before one of those actions, then you will notice that the metric is missing from the grid. To get the First Input Delay, close the extension, make a user action on the page, and then reopen.

  • Cumulative Layout Shift is an accumulation of shifts on the page. As you scroll through the page, you may see additional shifts and the extension will add new annotations dynamically. The popup grid that reports the total score will also increase as more shifts accrue.

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User reviews

100% useless. This extension automatically turns off every time you load a page. So, when you want to see what's causing the layout shifts that are killing your pagespeed performance score, when you load the page, you have to race to manually activate the extension for the page before it actually begins loading, which is, of course, humanly impossible. Then, whatever you do click it in time to show, it puts frames around things that have shifted, giving you exactly zero idea of what caused them to shift, so even if it worked from the beginning of the page load, it wouldn't be helpful in any way. Because you still don't know what caused the shifts.
by Penny Foriathotts, 2024-11-05

Works as shown, great tool!
by Stian Life, 2021-10-23
View all user reviews

Extension safety

Risk impact

Core Web Vitals Annotations does not require any sensitive permissions.

Risk likelihood

Core Web Vitals Annotations has earned a fairly good reputation and likely can be trusted.

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