INTEGRATION PREVIEW  —  Base Sepolia + zkVerify Volta

zkVerifier

zkVerifier is an integration-preview service that accepts UltraHonk proofs via the x402 protocol, settles USDC on Base Sepolia, and submits verified proofs to zkVerify Volta. We're in early integration preview; the API surface may change. 

# 1. Submit a proof → 201 with jobId + quote + fulfillUrl
import requests

# See /docs for a full example with fixture proof data
r = requests.post("https://zkverifier.net/v1/proofs",
    json={
        "proofType": "ultrahonk",
        "version": "V3_0",
        "proofData": { # { vk, proof, publicSignals } — fixture in /docs },
        "idempotencyKey": "my-agent-001",
    })
assert r.status_code == 201
body = r.json()
# → { jobId, proofHash, quote: { quoteCurrency, quoteAtomic, ... },
#      fulfillUrl, eventsUrl }

# 2. POST fulfillUrl WITHOUT X-PAYMENT → 402 with PaymentRequired
# The 402 body includes x402Version + accepts[] with network, asset, amount, payTo

# 3. Sign EIP-3009 transferWithAuthorization against accepts[0]
#    Domain: name="USD Coin", version="2", chainId=84532,
#    verifyingContract=0x036CbD53842c5426634e7929541eC2318f3dCF7e

# 4. Retry POST fulfillUrl with PAYMENT-SIGNATURE header (base64 JSON)
#    (X-PAYMENT is a documented alias)
r = requests.post(body["fulfillUrl"],
    headers={"PAYMENT-SIGNATURE": payment_b64})

# 5. Poll for status
r = requests.get(body["eventsUrl"])  # SSE stream of lifecycle events
Try the API → View specification

Why zkVerifier

  1. Built for x402 clients.

    Compatible with any client that emits x402Version: 2. Compatibility tests are in progress.

  2. Receipts are on-chain.

    USDC transfer on Base Sepolia + zkVerify Volta tx hash in one response.

  3. Operator stakes VFY. You pay USDC.

    No Substrate node in your stack.

Price

Testnet pricing is a fixed USDC floor; the live VFY oracle is being brought online.

How it works

  1. What an UltraHonk proof is.

    A compact zero-knowledge proof that verifies a computation without re-executing it. See the zkVerify docs.

  2. What x402 means.

    An open, neutral standard for internet-native payments between clients and servers. See x402.org.

  3. What zkVerifier receives.

    Your VK + proof bytes, and it returns a USDC challenge via the x402 protocol.

  4. What zkVerify Volta is.

    A high-performant, public, decentralized blockchain dedicated to zero-knowledge proof verification.

  5. How a receipt is constructed.

    USDC tx hash on Base + zkVerify inclusion hash, both in one response.