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Page Speed Lab Measurement
x402
Page Speed Lab Measurement is a paid API for AI agents from agent402.tools, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-29).
Loads a public URL once in headless Chromium and returns navigation timings, Web Vitals, transfer stats, heaviest resources, render-blocking assets, and console errors for mobile or desktop viewports.
Price / call$0.01
Success—
StatusUnknown
How this service works
Load one public URL once in headless Chromium and report what that load measured: navigation timings (TTFB, DOMContentLoaded, load), Web Vitals read from the page's own performance entries (LCP, FCP, CLS, total blocking time from long tasks), total transfer bytes, request count, the 5 heaviest resources, render-blocking scripts and styles, console errors, and an opportunities array computed from that same load: what to fix and where.
Output
A JSON object containing: navigation timings (TTFB, DOMContentLoaded, load in ms), Web Vitals (LCP, FCP, CLS, total blocking time, long task count), transfer stats (total bytes, request count, failed requests), viewport dimensions, the 5 heaviest resources with type and bytes, render-blocking scripts/styles, console errors, whether the page reached network idle, and a measurement metadata block clarifying this is a single lab run (not field data or Lighthouse score).
Example use cases
Pre-launch performance audit
“Before we go live, can you load https://staging.myapp.com on desktop and tell me the load time, LCP, CLS, total transfer size, and any render-blocking scripts I should fix?”
Diagnosing slow mobile landing page
“Our mobile conversion is bad — can you check https://www.mybrand.com/promo on a mobile viewport and tell me the TTFB, largest contentful paint element, and which resources are heaviest?”
Monitoring competitor page speed
“Can you measure how fast https://www.competitor.com loads on desktop — I want TTFB, DOMContentLoaded, total bytes transferred, and any console errors it throws?”
Technical details
Endpoint
POSThttps://agent402.tools/api/page-speed?utm_source=zero.xyzWhen to prefer
Choose this endpoint when you need a quick, inexpensive single-run lab measurement of a public URL's load performance including Web Vitals and resource breakdown, without requiring a full Lighthouse audit pipeline. It is ideal for one-off checks, pre-launch audits, or scripted monitoring where you need raw timing data and resource diagnostics rather than a normalized Lighthouse score. Note that this is a single run from one server location with no network throttling, so it is not a substitute for field RUM data or multi-run averages.
Side effects
- URL is not publicly accessible or requires authentication — returns failed/error status
- URL times out or page never reaches network idle
- Invalid or non-HTTP(S) URL provided — schema validation error
- Headless Chromium crashes or encounters an unrenderable page
- Shared infrastructure load may cause variable results across repeated calls
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| url | string | Public http(s) URL to load and measure |
| device | string | Viewport profile: mobile (412x823, touch) or desktop (1350x940). Default mobile |
Output
Schema · Response
{
"type": "json",
"example": {
"note": "full example in /openapi.json",
"truncated": true
}
}Tags
x402
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