Critical CSS Candidate Extractor
Use supplied coverage and HTML; preview candidate rules with explicit viewport limitations.
Extract conservative CSS candidates from exact source coverage, retaining structural at-rules and warning that one viewport is incomplete.
Using Critical CSS Candidate Extractor
Use supplied coverage and HTML; preview candidate rules with explicit viewport limitations.
- Start with Try worked example. Or open supported local evidence. [{url,ranges:[{start,end}]}] plus exact matching local CSS. This is coverage-driven, not an automatic critical-rendering-path audit.
- Use Details & settings to adjust the declared inputs, thresholds or component content. Review cards retain source evidence and any supported manual decisions.
- Open Preview for the actual analysis or interactive component. Test keyboard behavior and narrow layouts before relying on generated UI.
- Use Export for task artifacts and the complete workflow ZIP. Save review retains settings/decisions and source fingerprints; file-based projects need the original sources to reopen.
Example
The tailored example for Critical CSS Candidate Extractor demonstrates Extract conservative CSS candidates from exact source coverage, retaining structural at-rules and warning that one viewport is incomplete.
Questions & answers
What does Critical CSS Candidate Extractor support?
Extract conservative CSS candidates from exact source coverage, retaining structural at-rules and warning that one viewport is incomplete.
What input should I use?
[{url,ranges:[{start,end}]}] plus exact matching local CSS. This is coverage-driven, not an automatic critical-rendering-path audit.
What can I download?
Use the Export tab for task-specific artifacts, typed JSON, CSV and a workflow ZIP. Supported artifacts can include compressed files, reviewed CSS, source-position evidence, screenshot PNGs or qualified review reports.
Does this run a live website audit or deploy changes?
No. Performance diagnostics use imported evidence, explicit simulations or selected local bytes. Builders export code for you to review and integrate. No URLs are crawled, no service worker is installed and nothing is deployed. Public pages retain approved ads and optional consent-based analytics.
Related tools
A useful next step for your task.
Developer & DataHAR Network AnalyzerInspect a local HAR capture with request filters, timing waterfalls, status and domain summaries, request details, CSV exports and a minimized…
Developer & DataWeb App Manifest InspectorReview web-app names, start URLs, scopes, icons and display settings with resolved paths.
Developer & DataCSS Coverage Cleanup PlannerReview CSS coverage across multiple runs, inspect unused rule candidates, preview staged removals and export original/proposed CSS with a decision…
Developer & DataLayout Shift Evidence ExplorerReview layout-shift recordings with visual session windows, moved-element diagrams and repair notes. Inspect recent-input exclusions and export a…
Help improve this tool
Report a problem or suggest an improvement
Describe the issue without pasting private tool input. Feedback goes to our admin inbox.