# Web Evidence

> Web Evidence is a paid API for AI agents from api.williamrobinson.dev, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-12).

Fetches and extracts the readable content of a web page as Markdown, with integrity hash, for use as verifiable evidence

## Facts

- Endpoint: POST https://api.williamrobinson.dev/v1/web/evidence?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/web-evidence-6b576c8f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_LXBPtz-Wh3O8krQO89U5q

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 web-evidence-6b576c8f -d '<json body>'
```

Example prompt: Can you fetch the content of https://example.com/terms and extract it as readable markdown, up to 10000 characters, so I have a timestamped, integrity-verified copy of what it says right now?

## When to prefer this

Choose this endpoint when you need a lightweight, cheap ($0.01/call), cryptographically fingerprinted snapshot of a public webpage's readable content as Markdown — especially for evidence, auditing, or research. Unlike full notarized capture ($10/call on the same platform), this is optimized for fast text extraction with integrity hashing rather than full legal notarization. Prefer this over generic HTTP fetch tools when you need the SHA-256 integrity hash, language detection, and clean Markdown rendering via Chromium-readability.

## Known failure modes

- URL is unreachable or returns a non-200 status — source.status will reflect the HTTP error
- Page behind login or paywall — content may be empty or partial
- URL exceeds 2048 characters — request rejected
- maxChars below 1 or above 30000 — validation error
- Payment not attached — 402 response with payment-required header
- Network timeout during page load — error or empty result
- Dynamic JavaScript-heavy pages may yield incomplete extraction

## How this service works

Web Evidence ($0.01/call), OpenSCAD Print Validation ($0.05/call), Spreadsheet Modification & Audit ($0.05/call), Packing & Shipping Engineer ($0.05/call), Game-Asset Technical Artist ($0.10/call), PCB Fabrication Engineer ($0.25/call), Software Failure Reduction Lab ($0.50/call), Laboratory-Protocol Compiler ($0.15/call), Video Finishing & Localization ($0.50/call), Print Prototype Engineer ($0.15/call), Garment-Pattern Engineer ($0.10/call), Product-Label Artwork Compiler ($0.15/call) and Notarized Website Capture ($10.00/call), settled in USDC on Base mainnet over HTTP 402. No API keys, no accounts.

Price: $0.01 (10000 atomic USDC per call), settled over HTTP 402 (x402, scheme "exact", EIP-3009).

How to pay: an unpaid POST answers 402 with a base64 `payment-required` header describing an exact transfer of 10000 atomic USDC on eip155:8453 (asset 0x833589fcd6edb6e08f4c7c32d4f71b54bda02913) to 0x26026370fe8b2bb17af9092a17691c76519366da. Sign the EIP-3009 authorization, attach it in the `payment-signature` header, and retry the identical request. Invalid requests are never charged.

- Settlement: eip155:8453 / 0x833589fcd6edb6e08f4c7c32d4f71b54bda02913 / 0x26026370fe8b2bb17af9092a17691c76519366da

## Output

A JSON object containing: the page title, detected language, and full readable content as Markdown; the HTTP status, final (post-redirect) URL, original requested URL, and ISO timestamp of retrieval; load and extraction timing in milliseconds; a SHA-256 hash of the extracted content and the extraction engine version for integrity verification; and any warnings encountered during extraction.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "format": "uri",
   "maxLength": 2048
  },
  "maxChars": {
   "type": "integer",
   "default": 30000,
   "maximum": 30000,
   "minimum": 1
  },
  "includeLinks": {
   "type": "boolean",
   "default": false
  },
  "includeAccessibilityTree": {
   "type": "boolean",
   "default": false
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "page": {
   "title": "Example Domain",
   "language": "en",
   "markdown": "# Example Domain\n\nThis domain is for use in illustrative examples in documents.\n",
   "canonical": null
  },
  "source": {
   "status": 200,
   "finalUrl": "https://example.com/",
   "retrievedAt": "2026-01-01T00:00:00.000Z",
   "requestedUrl": "https://example.com/"
  },
  "timings": {
   "loadMs": 0,
   "extractMs": 0
  },
  "warnings": [],
  "integrity": {
   "sha256": "b6bdcd206468c6a8d071af581b180ce6a96166dddadc59b04acd4ee32a9c2ed3",
   "extractionVersion": "chromium-readability-1"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/web-evidence-6b576c8f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.williamrobinson.dev](https://www.zero.xyz/host/api.williamrobinson.dev/llms.txt)