# Vennatta Evidence Compare

> Vennatta Evidence Compare is a paid API for AI agents from vennatta-core.onrender.com, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-21).

Compares two versions of a text and returns bounded, hash-backed evidence of what changed between them.

## Facts

- Endpoint: POST https://vennatta-core.onrender.com/api/v1/evidence/compare?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-21
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/vennatta-evidence-compare-37167b7c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_TmSOI74vJ_SpPko8dDHab

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 vennatta-evidence-compare-37167b7c -d '<json body>'
```

Example prompt: Compare these two versions of the privacy policy and give me hash-backed evidence of exactly what changed — use 'policy' as the comparison type: [previous text] vs [current text].

## When to prefer this

Choose this endpoint when you need tamper-evident, hash-backed proof of exactly what changed between two known text versions — not just a raw diff. Ideal for compliance auditing, change monitoring, pricing surveillance, policy tracking, or integration documentation checks where you need a bounded, categorized evidence record rather than a simple line-by-line diff. Prefer it over generic diff tools when you need the comparison type context (pricing, policy, security, etc.) and a verifiable hash for both versions.

## Known failure modes

- Empty or missing current_text or previous_text returns a validation error
- Text exceeding 2,000,000 characters may be rejected or truncated
- Invalid comparison_type enum value returns an error
- Malformed source_url (non-HTTP/HTTPS URI) may cause a validation failure
- If the two texts are identical, the response may return an empty diff with no changes detected
- Payment failure or missing x402 payment header results in a 402 Payment Required error

## How this service works

Compare two supplied public-source text versions and return bounded, hash-backed evidence of change.

## Output

Returns a structured, bounded diff between the two supplied text versions, backed by hashes for each version, so the evidence of change is tamper-evident. Includes a categorized summary of what changed (e.g. pricing, policy, product, security, or integration context), the specific changed sections or passages, and cryptographic hashes for both the current and previous versions.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "source_url": {
   "type": "string",
   "format": "uri",
   "description": "Optional source URL associated with both submitted versions."
  },
  "current_text": {
   "type": "string",
   "maxLength": 2000000,
   "minLength": 1,
   "description": "Current version of the supplied public-source text."
  },
  "previous_text": {
   "type": "string",
   "maxLength": 2000000,
   "minLength": 1,
   "description": "Previous version of the supplied public-source text."
  },
  "comparison_type": {
   "enum": [
    "auto",
    "pricing",
    "product",
    "integration",
    "security",
    "policy"
   ],
   "type": "string",
   "default": "auto",
   "description": "Optional bounded category hint for the comparison."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/vennatta-evidence-compare-37167b7c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from vennatta-core.onrender.com](https://www.zero.xyz/host/vennatta-core.onrender.com/llms.txt)