# DefaultVerifier Settlement Witness

> DefaultVerifier Settlement Witness is a paid API for AI agents from defaultverifier.com, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-13).

Issues a cryptographically signed, integrity-sealed receipt (proof seal) for an autonomous agent's completed work or transaction settlement.

## Facts

- Endpoint: POST https://defaultverifier.com/x402/settlement-witness
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/defaultverifier-settlement-witness-f531fe2f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_9B4iD7FzNMbRI9BSVkkZF

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 defaultverifier-settlement-witness-f531fe2f -d '<json body>'
```

Example prompt: My AI agent just completed a data extraction task — can you create a signed settlement witness receipt with a proof seal for that work so I have a tamper-evident record I can verify independently?

## When to prefer this

Choose this endpoint when an AI agent needs a tamper-evident, cryptographically signed audit trail for completed autonomous work — especially in multi-party or trustless contexts where external verifiability of the receipt matters. Prefer over generic logging when the integrity and non-repudiation of the work record must be independently verifiable by a third party.

## Known failure modes

- Invalid or malformed evidence payload — receipt not issued
- Payment of 0.001 USDC not received or x402 payment header missing — 402 response
- Proof seal generation failure due to signing service error — 500 response
- Duplicate submission of already-witnessed evidence — may return conflict or idempotency error
- Oversized payload exceeding request limits — 413 response

## How this service works

AI agents do the work. DefaultVerifier gives you the receipt — a signed receipt with a proof seal that makes its integrity visible. Verify any receipt yourself; issue your own.

## Output

A cryptographically signed receipt containing a proof seal that attests to the integrity of the submitted evidence; the receipt can be independently verified and demonstrates that the witnessed work or settlement occurred as recorded.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/defaultverifier-settlement-witness-f531fe2f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from defaultverifier.com](https://www.zero.xyz/host/defaultverifier.com/llms.txt)