Page Existence Check

Assess whether a URL returns page content or missing-page signals. Returns an existence result, confidence and supporting checks.

Pay by wallet (x402) page-exists

Example

Example answer

{
  "url": "https://example.com",
  "title": "Example Domain",
  "exists": true,
  "reason": "ok",
  "signals": [],
  "final_url": "https://example.com/",
  "checked_at": "2026-08-12T12:00:00.000Z",
  "confidence": "medium",
  "redirected": false,
  "status_code": 200,
  "content_length": 559
}

Inputs

Field	Type	Required	What it is
`url`	string	Yes	URL to check for content-level existence
`timeout_ms`	integer	No	Request timeout in milliseconds (clamped to 1000-30000, default 10000)

Output fields

How reliably each field appears in a successful answer.

Field	Type	Appears
`url`	string	Always (present in every successful answer)
`error`	string	Sometimes (present only for some inputs)
`title`	string or null	Usually (present for most inputs)
`exists`	boolean or null	Usually (present for most inputs)
`reason`	one of ok, non_html_content, hard_404, soft_404_title, soft_404_body, soft_404_body_and_redirect, redirected_to_generic, thin_content, access_blocked, server_error, unexpected_status, timeout, redirect_loop, dns_error, network_error	Always (present in every successful answer)
`signals`	array	Always (present in every successful answer)
`final_url`	string or null	Usually (present for most inputs)
`checked_at`	string	Always (present in every successful answer)
`confidence`	one of high, medium, low, null	Usually (present for most inputs)
`redirected`	boolean	Always (present in every successful answer)
`status_code`	integer or null	Usually (present for most inputs)
`content_length`	integer or null	Usually (present for most inputs)

How to call it

The same tool through each route. MCP clients reach it through Strale’s server at https://api.strale.io/mcp; the call below is what the agent sends.

# Needs an API key. max_price_cents caps what this call may cost.
curl -X POST https://api.strale.io/v1/do \
  -H "Authorization: Bearer $STRALE_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
    "capability_slug": "page-exists",
    "inputs": {
      "url": "https://strale.dev"
    },
    "max_price_cents": 2
  }'

{
  "tool": "strale_execute",
  "arguments": {
    "slug": "page-exists",
    "inputs": {
      "url": "https://strale.dev"
    },
    "max_price_cents": 2
  }
}

import { Strale } from "straleio";

const strale = new Strale({ apiKey: process.env.STRALE_API_KEY! });
const result = await strale.do({
  capability_slug: "page-exists",
  inputs: {
    "url": "https://strale.dev"
  },
  max_price_cents: 2,
});

import os
from straleio import Strale, DoRequest

strale = Strale(api_key=os.environ["STRALE_API_KEY"])
result = strale.do(DoRequest(
    capability_slug="page-exists",
    inputs={
        "url": "https://strale.dev",
    },
    max_price_cents=2,
))

# No account. The first request answers 402 with the price in USDC;
# an x402 client pays it from your wallet and repeats the request.
curl -i -X POST https://api.strale.io/x402/v2/page-exists \
  -H 'Content-Type: application/json' \
  -d '{
    "url": "https://strale.dev"
  }'

Limitations

Single-page apps can hide missing pages
Some JavaScript applications return the same HTTP 200 page for every URL, including removed listings. These can return `exists` true with medium confidence even when the requested listing is missing.
What to do instead: For known SPA domains, corroborate with a rendered check (screenshot-url) before trusting exists:true.
Soft-404 phrase heuristics are English-only
Removal and error-page phrases are recognised only in English. Non-English error pages can be misclassified as existing content.
What to do instead: For non-English sites, verify the returned title and final_url yourself rather than trusting exists alone.
Blocked pages return unknown and are still billed
Pages returning HTTP 401 or 403 produce `exists` null with reason access_blocked, rather than a determination that the page exists. This completed check is billed, and unknown results can be common on sites that block automated requests.
What to do instead: Treat exists:null as "unknown" and fall back to a manual check or a different data source for these domains.
Low-confidence negatives can misread live pages
Redirects to generic pages and thin-content checks can classify legitimate pages as missing with low confidence. Confirm low-confidence negatives before acting.
What to do instead: Only act automatically on confidence high/medium; route confidence:low results to a secondary check.