Core Web Vitals Audit & Fix Kit: LCP, INP & CLS Checklist, Tracker & Client Report
by CoreCodify
$29
Find out why a client site is slow, fix it in the right order, and prove it.
A red PageSpeed score, a Search Console "Core Web Vitals issues" email, or a client saying "the site feels slow". This kit gives you a repeatable way to go from that message to a diagnosis, a prioritised fix list and a before/after report backed by real-user field data. It covers LCP, INP and CLS on WordPress, Shopify, Webflow, Framer and Next.js sites.
What's inside
Core-Web-Vitals-Audit-Guide.pdf (29 pages): the metrics and thresholds in plain English, field vs lab data (why PageSpeed says 45 while Search Console says Good), the audit method, 5 step-by-step test protocols, the 71-check checklist, fix recipes with code, third-party script triage, platform notes, scoring and budgets, real-user monitoring, before/after evidence, reporting, selling the service, client scripts and a fictional worked example.
CWV-Audit-Tracker.xlsx (8 tabs): Pages (type the p75 values and Good / Needs improvement / Poor plus "Passes CWV?" fill themselves), Checklist (71 checks), Issues Log (priority and quick-win formulas), Third Parties, Before-After, Budget and Dashboard.
CWV-Audit-Report-Template.docx: a white-label client report covering summary, field results, diagnosis, issues and fixes, third-party plan, budget and limitations.
Monthly-Performance-Report-Template.docx: a one-page monthly update for care-plan clients.
Quick-Start.pdf: your first audit in about 90 minutes. Also START-HERE.md and LICENSE.txt.
The 5 test protocols
A · Field data: PageSpeed Insights (CrUX) and the Search Console Core Web Vitals report
B · Lab baseline: Lighthouse 13, mobile, median of 3 runs
C · Trace the LCP: find the LCP element and its biggest sub-part (TTFB, load delay, load duration, render delay)
D · INP interactions: live metrics with CPU throttling, plus input delay, processing and presentation
E · CLS hunt: layout shifts on load and on scroll, and their likely culprits
71 checks in 9 areas
Field data and measurement · Server, TTFB and caching · LCP element and loading path · Images and media · CSS and web fonts · JavaScript and interactivity · Third-party scripts · Layout stability · Navigation, bfcache and delivery. Every check comes with a "how to test" step, the metric it moves and a default severity.
Facts checked on 10 Nov 2026
Thresholds at the 75th percentile: LCP ≤ 2.5 s, INP ≤ 200 ms, CLS ≤ 0.1 (poor above 4.0 s, 500 ms and 0.25). Source: web.dev
INP replaced FID as a Core Web Vital on 12 March 2024. Lighthouse 13 swapped many audits for "insights" (latest release 13.6.0)
HTTP Archive Web Almanac 2025: only 48% of mobile websites had good Core Web Vitals
Platform notes checked against the WordPress 6.3, Shopify image_tag and Next.js 16 Image docs
Who it's for
Freelance web developers and small agencies who build or maintain client sites
Anyone who wants to sell a scoped speed audit and the optimisation work that follows (package ideas and proposal wording included)
Care-plan providers who want a monthly performance report
Good to know
Everything is documents and templates. Works in Excel, Google Sheets, Word, Google Docs and LibreOffice.
Honest by design: there are no "100 score" or ranking promises. Google itself says good Core Web Vitals don't guarantee top rankings.
Field data uses a 28-day window, and the kit shows you how to report lab results now and field results later.
Licence: use it on your own and client sites and deliver white-label reports. Please don't resell or share the kit.