# Page Speed Lab Measurement

> 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.

## Facts

- Endpoint: POST https://agent402.tools/api/page-speed?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/page-speed-lab-measurement-0da59e6e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_MEfNVF0wJaK1R26LW9aQJ

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability page-speed-lab-measurement-0da59e6e -d '<json body>'
```

Example prompt: Can you load https://www.example.com in a mobile viewport and report the TTFB, LCP, total page weight, any render-blocking resources, and console errors?

## When to prefer this

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.

## Known failure modes

- 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

## 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).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "description": "Public http(s) URL to load and measure"
  },
  "device": {
   "enum": [
    "mobile",
    "desktop"
   ],
   "type": "string",
   "description": "Viewport profile: mobile (412x823, touch) or desktop (1350x940). Default mobile"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "note": "full example in /openapi.json",
  "truncated": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/page-speed-lab-measurement-0da59e6e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent402.tools](https://www.zero.xyz/host/agent402.tools/llms.txt)