CartHacker Core Web Vitals Monitoring

Description

Google uses Core Web Vitals in its ranking systems and recommends good scores for success in Search. This plugin measures all three metrics on your real visitors and shows Core Web Vitals right in your WordPress admin. You’ll see whether your site passes the way Google judges it and fix a slow or jumpy page before it costs you visitors from Google.

Google’s own data comes from the Chrome UX Report behind PageSpeed Insights and Search Console. It covers the last 28 days and only shows up once your site has enough Chrome traffic.

This plugin starts counting with your first visitor, so you’ll know this week whether a new theme, plugin or cache setting made your site faster or slower.

It measures Loading (Largest Contentful Paint), Responsiveness (Interaction to Next Paint) and Visual stability (Cumulative Layout Shift) on every real visit and shows pass or fail the way Google judges it: 75% of visits must meet each target. You also get traffic statistics on your visitors, a free weekly report and an email alert when your site gets slower.

What you get

• Loading (Largest Contentful Paint): how fast the biggest image or headline appears. Pass: under 2.5 seconds.
• Responsiveness (Interaction to Next Paint): how fast the page reacts to a tap or a click. Pass: under 200 milliseconds.
• Visual stability (Cumulative Layout Shift): how much the page jumps while it loads. Pass: under 0.1.
• Pass or fail for each one, with the share of good visits behind the verdict.
• A daily speed chart that shows the exact day your site got slower.
• Server response time (Time to First Byte): how fast your server starts sending each page, day by day on the same chart.
• Elements that make your pages jump: the parts of the page that moved most on the visits that lost a Good Visual stability score, such as Related products or a cookie banner, and what to do about the first one.
• Traffic statistics: page views, unique visitors, devices, browsers and operating systems, all counted without cookies.
• Your scores on the WordPress dashboard every time you sign in.
• A free weekly report and a slowdown alert by email.

Free and CartHacker Premium

The free CartHacker account measures up to 1,000 page views a day and keeps 7 days of speed and traffic history. The weekly report and the slowdown alert are included.

CartHacker Premium ($7.99 a month or $79 a year, USD) keeps 180 days of history, measures up to 50,000 page views a day, splits speed by page type, shows real-visitor speed for each of your busiest pages and runs automatic speed reports on your 50 most visited pages at least once a week. You’ll see it in this plugin and in the full Core Web Vitals Monitoring report on carthacker.com. The same membership also gives you all 50 trust badges in 30 languages, unlimited PDF tools, 200 tracked QR codes, no ads on CartHacker, new guides 2 weeks earlier and new CartHacker tools as they launch.

How it works

Once you connect, the plugin adds a small measuring script to your public pages. The script is served from your own site and loads deferred, so it never holds up your page. It sends one short report per page view to carthacker.com.

The script sets no cookies and stores nothing on the visitor’s device. You don’t need to add anything to your cookie consent banner.

The plugin doesn’t count visits from logged-in administrators, editors and authors. That way your own clicks around the site don’t change your scores. To count them too, turn on Measure logged-in editors in Site settings on the plugin page.

Fonts

The plugin screens use two open-source fonts, bundled in assets/fonts: Inter by Rasmus Andersson and JetBrains Mono by JetBrains. Both are free under the SIL Open Font License 1.1.

Source code

Every file in this plugin is readable source code with no build step. The script that measures your visits is assets/js/ch-monitor.js.

External services

This plugin uses the CartHacker service (https://carthacker.com), run by CARTHACKER LLC, to collect the measurements and show the results. It connects to carthacker.com only after an administrator clicks Start free monitoring on the plugin page and confirms the connection on carthacker.com.

• Connecting. The button opens https://carthacker.com/connect/ in your browser and sends this site’s address, the address of the plugin page, which CartHacker plugin is connecting, whether WooCommerce is active and one-time security values (an OAuth state and a PKCE challenge). After you confirm, your site sends the one-time code, the PKCE verifier, the site address and the plugin version to https://carthacker.com/wp-json/carthacker/v1/connect/token. It receives an access token and stores it in your site’s database.
• Measuring. While connected, every public page loads the plugin’s measuring script. Once per page view, the browser sends one request to https://carthacker.com/ch-monitor/hit. It goes out when the visitor leaves the page or switches tabs, or after five minutes on the page. The request contains the site key and the page path. On a site whose addresses name the page with a query parameter, such as ?product=linen-shirt or ?route=product/product, that parameter is included too. The rest of the query string and anything after a # is removed. The request also contains the platform and kind of page, the network type the browser reports, the width of the browser window and the timings: Largest Contentful Paint, Interaction to Next Paint, Cumulative Layout Shift, Time to First Byte, First Contentful Paint and the total load time. If the page moved while it loaded, the request also says which element moved the most (its tag, id and class names, never its text), when it moved and whether the page had finished loading at that moment. From the request, CartHacker works out the browser and operating system family, the device class and the country. It counts unique visitors with a daily code: a one-way hash of the visitor’s IP address, browser string and the date, so the code changes every day. The IP address itself is not stored.
• Reading your results. When you open the plugin page or the WordPress Dashboard, your site’s server calls https://carthacker.com/wp-json/carthacker/v1/plugin/status and https://carthacker.com/wp-json/carthacker/v1/plugin/stats with the access token and the plugin version. It reuses each answer for 15 minutes unless you click Refresh report. Once a day, your site also calls /plugin/status on its own to read the plan and the site key.
• Disconnecting. Clicking Disconnect now, or deleting the plugin, sends one request with the access token to https://carthacker.com/wp-json/carthacker/v1/plugin/disconnect.

CartHacker Terms of Service: https://carthacker.com/terms/

CartHacker Privacy Policy: https://carthacker.com/privacy/