# DELTA Witness — Web Capture & Proof Service

> DELTA Witness — Web Capture & Proof Service is a paid API for AI agents from delta-witness-api.ruphussten.workers.dev, paid per call via x402, $1/call, status unknown (last checked 2026-09-15).

Captures a public webpage and returns a machine-verifiable cryptographic proof bundle with a tamper-evident hash and timestamped manifest.

## Facts

- Endpoint: POST https://delta-witness-api.ruphussten.workers.dev/v1/capture
- Price: $1/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/delta-witness-web-capture-proof-service-4433f855
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_weR1JW_4XxafHrIhMS-Mb

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 delta-witness-web-capture-proof-service-4433f855 -d '<json body>'
```

Example prompt: Capture and create a cryptographic proof of what https://example.com/pricing currently shows, so I have a verifiable timestamped record I can reference later.

## When to prefer this

Choose this endpoint when you need a cryptographic, timestamped proof that a specific public URL contained particular content at a specific moment — especially for autonomous agent workflows where decisions must be auditable, for compliance use cases requiring tamper-evident records, or for dispute resolution where a screenshot is insufficient and machine-verifiability matters. Prefer this over simple HTTP fetching or screenshot tools when the downstream requirement is a verifiable hash/manifest rather than raw HTML.

## Known failure modes

- URL is not publicly accessible or returns a non-2xx status — capture fails with an error
- URL does not match the required https?:// pattern — rejected at input validation
- Payment (x402) not provided or insufficient — 402 Payment Required response
- Target page requires JavaScript rendering that the capture service cannot execute — partial or empty capture
- Rate limiting or upstream timeout on the target URL — capture may time out or return incomplete data

## How this service works

Paid, machine-verifiable capture and preflight checks for public web sources.

## Output

A JSON object containing: a boolean success flag, product type ('capture'), a unique proof_id UUID, a SHA-256 bundle_root hash of the captured content, an observed_at ISO timestamp, a manifest_url pointing to the full proof manifest, and a public_proof_url for human-readable verification.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "url": {
   "type": "string",
   "pattern": "^https?://",
   "description": "Public HTTP(S) webpage to observe."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "ok": true,
  "product": "capture",
  "proof_id": "7d9d12f7-8f91-5f41-9f0c-5ef257d9ea5d",
  "bundle_root": "sha256:0000000000000000000000000000000000000000000000000000000000000000",
  "observed_at": "2026-08-31T00:00:00.000Z",
  "manifest_url": "https://delta-witness-api.ruphussten.workers.dev/v1/proofs/7d9d12f7-8f91-5f41-9f0c-5ef257d9ea5d",
  "public_proof_url": "https://delta-witness-api.ruphussten.workers.dev/p/7d9d12f7-8f91-5f41-9f0c-5ef257d9ea5d"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/delta-witness-web-capture-proof-service-4433f855/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from delta-witness-api.ruphussten.workers.dev](https://www.zero.xyz/host/delta-witness-api.ruphussten.workers.dev/llms.txt)