See which blocks load which CSS/JS assets on a page and estimate their weight.

devmarvs

Block Weight Inspector adds a sidebar panel in the block editor that maps blocks in the current post/page to the CSS and JS assets they register. It estimates local asset sizes, highlights top offenders, and exports a JSON report. It can also generate a suggested conditional-loading snippet to help you dequeue assets when a block is not present. 
It also adds a Tools -> Block Weight Inspector screen for auditing existing posts without opening the editor. 
Note: The inspector preserves block comment delimiters when analyzing content so <code>parse_blocks()</code> remains accurate after sanitization.
Key features:
<ul>
<li>Block -> asset mapping using registered block metadata.</li>
<li>Estimated size for local assets.</li>
<li>Top offenders summary and full asset list.</li>
<li>JSON export for sharing or auditing.</li>
<li>Suggested conditional-loading rules (review before use).</li>
</ul>

Alternatives to Block Weight Inspector

Top alternatives