# does-site-use-web-vitals-script

> does-site-use-web-vitals-script is a paid API for AI agents from site.intel.rallylive.ca, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-15).

Checks whether a website's homepage uses the web-vitals JavaScript library by fingerprinting its HTML and response headers, returning a yes/no answer with evidence.

## Facts

- Endpoint: GET https://site.intel.rallylive.ca/site/uses/web-vitals-script?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/does-site-use-web-vitals-script-572445e7
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_SwEpMKfvQO_5vm_PAv2iG

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 does-site-use-web-vitals-script-572445e7
```

Example prompt: Can you check if shopify.com is using the web-vitals script on its homepage? I want to know if they're tracking Core Web Vitals performance metrics.

## When to prefer this

Use this endpoint when you need a fast, low-cost ($0.01) single-domain check for web-vitals script presence as part of sales prospecting, competitive intelligence, or migration planning. Prefer this over bulk endpoints when checking one domain at a time or when you need immediate yes/no results with evidence. Choose this over generic website crawlers when you specifically need technographic data about web-vitals adoption.

## Known failure modes

- Domain is unreachable or returns a non-200 status — result may be inconclusive or an error
- The site serves a JavaScript-rendered SPA where web-vitals is loaded dynamically — static fingerprinting may return false negative
- Minified or obfuscated script names may evade fingerprint matching
- Rate limiting or bot protection on the target site may block the fetch

## How this service works

Does a website use web-vitals script? Fetches the page (homepage for a bare domain) and matches web-vitals script's fingerprints in the HTML and response headers, returning yes/no with the evidence snippet and the category (performance). Technographics for sales, competitor research and migration planning, one technology per call. $0.01 per check.

## Output

Returns a yes/no boolean indicating whether the web-vitals script was detected on the site's homepage, along with the matching evidence snippet found in the HTML or response headers, and the technology category label (performance).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/does-site-use-web-vitals-script-572445e7/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from site.intel.rallylive.ca](https://www.zero.xyz/host/site.intel.rallylive.ca/llms.txt)