---
title: "Independent ProofGuard attestation of an x402 endpoint"
method: POST
path: "/proofguard/attest"
tags: ["ProofGuard"]
---

# Independent ProofGuard attestation of an x402 endpoint

`POST /proofguard/attest`

SolSigs ProofGuard independent attestation — live unpaid 402-level probe of any x402 endpoint, returning an Ed25519-signed receipt (verification_mode: proofguard_probed); optionally queues on-chain feedback to the 8004 Agent Registry on Solana mainnet. 0.50 USDC.

## Request body

- object
  - `target_url` string, uri, required — x402 endpoint to probe (https, public hosts only)
  - `method` string
  - `asset_8004` string — Optional registered 8004 agent asset address — queues on-chain feedback

## Response `200`

Ed25519-signed ProofGuard probe receipt (verification_mode: proofguard_probed), receipt URL, and attestation queue reference when asset_8004 was supplied

## Other responses

- `400` — Invalid target URL, private/loopback host, or bad asset address
- `402` — Payment required — 0.50 USDC via x402 on Solana mainnet

---

[API](https://skmtc.net/solsigs/apis/solsigs-solana-data-apis-for-ai-agents.md) · [All operations](https://skmtc.net/solsigs/apis/solsigs-solana-data-apis-for-ai-agents/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/solsigs/solsigs-solana-data-apis-for-ai-agents/revisions/296e44870ad2/schema)