# CSS Preload Href Extractor

> CSS Preload Href Extractor is a paid API for AI agents from agentshelf.syntexa.ch, paid per call via x402, $0.007/call, status unknown (last checked 2026-10-02).

Extracts preload hrefs from link[rel='preload'] elements in a public webpage or raw HTML, returning the list of preloaded resource URLs.

## Facts

- Endpoint: POST https://agentshelf.syntexa.ch/v1/css-preload?utm_source=zero.xyz
- Price: $0.007/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-02
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/css-preload-href-extractor-c7be44fd
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_-mMtAtT5j-AgZ5w-VyMLW

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 css-preload-href-extractor-c7be44fd -d '<json body>'
```

Example prompt: Can you extract all the preload hrefs from https://example.com — I want to see which resources that page declares as link[rel='preload'].

## When to prefer this

Use this endpoint when you need to specifically extract link[rel='preload'] resource hints from a public webpage or HTML string, such as auditing what assets a page preloads, analyzing performance strategies, or building tooling around browser resource hints. Prefer the free /v1/sandbox/css-preload endpoint first if available. Choose this over general HTML scrapers when you specifically need structured preload href data rather than full page content.

## Known failure modes

- URL is unreachable or returns non-200 status — extraction fails with error
- HTML exceeds 200,000 character limit — request rejected
- URL is flagged as SSRF-unsafe (private/internal IP range) — blocked
- No link[rel='preload'] elements found — returns empty list
- Malformed HTML prevents parsing — may return empty or partial results
- URL string shorter than 8 characters — validation error

## How this service works

Call when an agent needs preload hrefs via link[rel='preload'] from a public page or HTML (SSRF-safe). Exact $0.007 USDC. Prefer unpaid POST /v1/sandbox/css-preload first.

## Output

A list of href values found in link[rel='preload'] elements from the given page or HTML. Each entry represents a resource URL that the page declares as a preload hint, such as fonts, scripts, stylesheets, or images.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "maxLength": 2048,
   "minLength": 8,
   "description": "Public page to fetch. The selector or profile is fixed by the SKU. Provide url or html."
  },
  "html": {
   "type": "string",
   "examples": [
    "<!doctype html><html lang=\"en\"><head><title>Hello</title>\n<meta charset=\"utf-8\"><meta name=\"description\" content=\"Desc\">\n<link rel=\"canonical\" href=\"https://example.com/\"><link rel=\"icon\" href=\"/favicon.ico\">\n</head><body><h1>Hello</h1><a href=\"https://example.com/a\">A</a></body></html>"
   ],
   "maxLength": 200000,
   "minLength": 1,
   "description": "HTML to extract from locally. Provide html or url. When both are set, html is used."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/css-preload-href-extractor-c7be44fd/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agentshelf.syntexa.ch](https://www.zero.xyz/host/agentshelf.syntexa.ch/llms.txt)