CLS Image Scanner - Sitemap & Layout Shift Tool

Identify images missing width/height causing CLS. Scan pages or bulk-scan full Sitemaps. Dashboard & Export.

CLS Scanner - Sitemap & Layout Shift Tool is a practical, performance-first Chrome extension built for technical SEO specialists, web developers, agencies, QA teams, and site owners who want to diagnose and fix image-related Cumulative Layout Shift issues quickly. If your team cares about Core Web Vitals, visual stability, Lighthouse outcomes, and real-world user experience, this extension gives you a focused workflow for detecting layout-shift risks from images and turning audit data into action. Most performance tools are broad. CLS Scanner is specific. It concentrates on one high-impact area that often gets ignored during content updates, design refreshes, and template edits: image sizing behavior across real pages. Missing width and height attributes, broken aspect-ratio patterns, oversized assets, weak alt text practices, and inconsistent layout reservation all quietly increase CLS risk. This extension is designed to surface those issues in a clear, sortable, exportable format so teams can prioritize fixes faster. The extension supports single-page scanning and nested sitemap auditing. On a single page, you can detect image assets, inspect rendering behavior, review dimensions, and find risky metadata patterns. On larger sites, you can load a sitemap, traverse nested sitemap trees, select exactly which URLs to analyze, and run bulk audits without losing control over scope. This is useful for enterprise sites, agency client audits, and pre-launch QA for large content libraries. Core use cases include Core Web Vitals optimization, technical SEO audits, migration QA, redesign regression checks, and client reporting. If your team regularly answers questions like “Why is CLS unstable after template updates?”, “Which pages still miss image width and height?”, “Which assets are causing avoidable layout movement?”, or “How do we export clean audit proof for clients?”, CLS Scanner is built for that workflow. WHAT THE EXTENSION HELPS YOU FIND 1) Missing HTML width and height on inline images. 2) Image assets that appear safe versus those with direct layout-shift risk. 3) Page-level context that can align with PageSpeed diagnostics. 4) Image format opportunities, including modern format checks. 5) Alt text quality and accessibility-related image metadata issues. 6) Rendered size versus source size mismatch that impacts performance. 7) URL-level summaries that make bulk prioritization easier. 8) Export-ready evidence for stakeholders who need actionable reports. WHY THIS MATTERS FOR SEO AND USER EXPERIENCE Cumulative Layout Shift is a Core Web Vitals metric that affects perceived stability and trust. Unstable pages create frustration, accidental clicks, and poor reading flow. On content-heavy websites, especially sites with blogs, marketing pages, product catalogs, and landing pages, image loading and sizing patterns are a common CLS trigger. Teams often detect these issues too late, after release, when rankings, conversion behavior, or user satisfaction have already dropped. CLS Scanner gives your team a preventive workflow and a repeatable review process. SINGLE PAGE SCAN WORKFLOW Use the side panel or popup scan flow to inspect the active page quickly. The extension evaluates image-related layout behavior and organizes findings for fast triage. This mode is ideal when you are debugging a specific URL, validating a fix before deployment, reviewing new content, or checking template changes after a CMS update. You can inspect image URL context, dimensions, alt text, and issue tags in one place. BULK SITEMAP SCAN WORKFLOW Load a sitemap URL, parse nested sitemap trees, filter and select target URLs, and run the audit flow across selected pages. This lets technical teams move from one-off spot checks to broad, structured auditing. Instead of guessing where issues might exist, teams can scan meaningful page sets and measure improvement from one run to the next. This is especially useful for agencies who need to evaluate multiple sections of a client site and present clear change summaries. NESTED SITEMAP AWARENESS Large sites often use sitemap indexes and nested sitemap files for posts, pages, categories, products, docs, or region-based content groups. CLS Scanner is designed to support this structure and help you choose what to scan. This keeps the audit process practical. You can target critical sections first, avoid noisy URLs during early review, and run broader coverage when needed. PAGESPEED CONTEXT SUPPORT When a PageSpeed API key is configured, the extension can enrich image audit workflows with page-level context. This supports deeper analysis when teams want to compare direct image findings with PSI-style signal patterns. It is useful for teams that already use Lighthouse, CrUX, or PageSpeed in their reporting and need image-level detail alongside page-level data. EXPORTS FOR REAL WORK Audit insights are only useful if teams can share and act on them. CLS Scanner includes export options to support different workflows: - CSV export for spreadsheet workflows and sorting in tools like Google Sheets or Excel. - JSON export for engineering workflows, automation, or internal tooling. - HTML export for portable, shareable report snapshots. - PDF-friendly workflow for stakeholder-ready deliverables. These export modes help bridge communication between SEO, development, design, project management, and clients. Teams can move from diagnosis to implementation without reformatting data manually. DESIGNED FOR AGENCY REPORTING Agencies need speed, consistency, and proof. CLS Scanner helps agencies capture repeatable evidence of image-related layout risk, compare scans, and show measurable progress. It is useful during onboarding audits, monthly maintenance, technical SEO retainers, redesign QA, and post-fix verification. Instead of sending raw screenshots, teams can send structured exports with URL-level context and issue signals. DESIGNED FOR DEVELOPERS Developers need precise signals, not vague recommendations. The extension focuses on actionable image-related checks that map to real frontend fixes, including width and height attributes, layout reservation patterns, and asset-level metadata quality. This reduces time spent guessing root cause and helps teams prioritize fixes that improve user-visible stability. DESIGNED FOR SEO SPECIALISTS Technical SEOs need to identify issues at scale and communicate impact clearly. With sitemap scanning and exportable reporting, the extension supports SEO workflows where prioritization and cross-team communication matter. It can be used during audits, migrations, content expansion, and ongoing Core Web Vitals monitoring routines. DESIGNED FOR CONTENT AND MARKETING TEAMS Content teams publish frequently. Small image mistakes can silently degrade visual stability over time. CLS Scanner helps teams catch those issues before they spread across templates and archives. This reduces performance debt and keeps user experience more consistent. FEATURE HIGHLIGHTS - Focused CLS image auditing workflow. - Current page scan from side panel or popup. - Nested sitemap parsing and URL selection. - Bulk scanning workflow for selected URLs. - Issue-focused asset table for triage. - Metadata checks for dimensions and alt text quality. - Format and size context for optimization decisions. - Page-level context support when API data is available. - History-aware workflow for comparing progress. - CSV, JSON, HTML, and PDF-oriented export support. PRO MODE POSITIONING Free mode supports practical auditing for smaller scope checks. Pro mode is positioned for teams that need broader sitemap coverage, stronger bulk workflows, and larger audit operations. This tiering is useful for freelancers, growing agencies, and teams scaling their technical SEO process. QUALITY OF LIFE BENEFITS - Faster investigation of layout-shift complaints. - Clearer handoff from audit to implementation. - Easier collaboration between technical and non-technical stakeholders. - Cleaner reporting for client communication. - Reduced time spent collecting manual evidence. - Repeatable process for pre-release performance QA. HOW TEAMS TYPICALLY USE CLS SCANNER - Scenario 1: Pre-launch QA Before launch, the team scans priority landing pages and templates, identifies missing dimensions, and fixes risky image markup. - Scenario 2: Monthly technical SEO review The SEO team runs sitemap-based audits on key sections and exports findings for developers. - Scenario 3: Client reporting An agency runs a baseline scan, applies fixes, reruns the audit, and shares exportable evidence of improvement. - Scenario 4: Redesign regression check After UI changes, the team validates whether updated components preserved image layout stability. - Scenario 5: Content expansion As new articles and pages are published, editors and SEO specialists periodically check image behavior to avoid accumulating CLS debt. PRIVACY AND DATA HANDLING SUMMARY Core scanning behavior runs locally in the browser. Settings, scan history, and stored audit data are saved in Chrome storage. Optional PSI enrichment sends audited page URLs to Google PageSpeed Insights when configured. License activation sends required licensing data to Lemon Squeezy. Optional analytics, when enabled by publisher configuration, can be routed without storing audited page URLs or license keys in analytics payloads. This product is designed to keep audit workflows practical while respecting privacy expectations. Users and teams should review the published privacy policy for complete disclosure. WHAT MAKES THIS DIFFERENT FROM GENERIC SEO EXTENSIONS Many SEO extensions are broad and shallow. CLS Scanner is intentionally narrow and deep on image-related layout stability. It is built for teams that need focused diagnostics and high-quality exports, not just a quick score. By centering image layout behavior and sitemap-level scalability, it fills a specific gap in technical SEO and frontend performance workflows. HOW THIS SUPPORTS CORE WEB VITALS IMPROVEMENT CLS is easier to improve when teams can isolate real asset-level causes. This extension helps teams: - Locate missing dimension patterns quickly. - See where layout reservation is present or missing. - Understand image sizing mismatch in practical terms. - Organize issues by priority. - Export findings into implementation-ready formats. - Validate progress across repeat scans. WHO SHOULD INSTALL THIS - Technical SEO consultants who deliver audit reports. - Frontend developers responsible for stable rendering. - Agencies that manage multiple client sites. - Performance specialists working on Core Web Vitals. - Founders and product teams who want cleaner UX and stronger performance hygiene. - Publishers and content platforms with frequent image updates. WHEN THIS TOOL IS MOST VALUABLE - During migration from one theme/template system to another. - During high-volume content publishing periods. - During redesign cycles where component markup changes. - During Core Web Vitals optimization initiatives. - During enterprise SEO audits requiring URL-level evidence. TEAM COMMUNICATION BENEFITS - SEO can present clear issue lists instead of abstract warnings. - Developers receive specific assets and page context to fix. - Project managers get exportable proof for prioritization. - Clients receive structured reports instead of fragmented screenshots. SCALABILITY BENEFITS - Single-page scan for quick checks. - Sitemap-based flow for broad coverage. - Selectable URL scope for controlled audit batches. - Export support for custom internal workflows. PERFORMANCE CULTURE BENEFITS - Creates a repeatable process for layout stability. - Reduces reactive firefighting after release. - Supports preventive QA before user impact grows. - Makes technical debt visible in a format teams can act on.