IconVault's Performance Budget tool helps you keep websites fast by setting a weight budget per asset type and checking what passes. Click Scan this page to read the real network assets of this page through the browser's Resource Timing API, or build a manual asset list when planning a page you have not built yet, then set budgets for JavaScript, CSS, images, fonts and other assets and get an instant pass or fail verdict per type.

You also get rough load-time estimates for Slow 3G, 4G and WiFi, a sortable asset table with sizes, and a CSV export of your asset inventory. It is free and runs fully in your browser. The honest caveat: load times are simple weight-divided-by-throughput estimates that ignore latency, render blocking and caching, and cached assets may report 0 bytes, so treat them as a planning signal rather than a lab measurement.