Find blocking scripts
Check scripts without async, defer, or module hints to spot possible parsing delays.
Web Performance Analyzer
Analyze webpage resource counts, file sizes, load times, and basic performance issues.
Web Performance
Web performance precheck tool
This precheck parses HTML structure, counts elements, scripts, stylesheets, images, and preload hints, then flags possible render blocking, layout shift, and resource-priority issues. It is a source-level early review and does not pretend to measure network speed, Core Web Vitals, or Lighthouse scores.
Protect layout stability
Check image dimensions to reduce layout movement when images load.
Source-level metrics
Summarize HTML size, nodes, and resource counts for a quick review before real monitoring.
How to use
- Paste page HTML with its actual head, body, script, link, and img structure.
- Run the precheck to see counts, score, and itemized findings.
- Apply the suggestions, then validate with real browsers, network tests, and performance monitoring.
FAQ
Does it measure real load speed?
No. It only parses pasted source and cannot know server response, cache, network, device CPU, actual image transfer, or runtime scripts. Use browser performance tools or monitoring on the real URL for measurements.
Why declare image dimensions?
The browser can reserve space before an image arrives, reducing movement of following content. It is a structural hint and still needs responsive CSS and real asset ratios.
Recommended utilities
You may also need these file utilities
Web Meta Checker
Check webpage title, description, canonical, robots, Open Graph, and other metadata.
Web Link Checker
Check internal links, external links, image URLs, and common broken-link issues on a webpage.
Webpage Screenshot
Capture the visible area or full webpage from a URL with common desktop and mobile viewport sizes.