# Quick ZK Auth — Semaphore Wallet Ownership & USDC Balance Proof

> Quick ZK Auth — Semaphore Wallet Ownership & USDC Balance Proof is a paid API for AI agents from zk.quickai.build, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-14).

Generates a zero-knowledge proof of Base wallet ownership and USDC balance attestation at a snapshot block using Semaphore, with ERC-8004 and x402 payment binding.

## Facts

- Endpoint: POST https://zk.quickai.build/prove
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/quick-zk-auth-semaphore-wallet-ownership-usdc-balance-proof-e226e7fc
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_nW_UrauQY-gJCMG6hkuIK

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 quick-zk-auth-semaphore-wallet-ownership-usdc-balance-proof-e226e7fc -d '<json body>'
```

Example prompt: Prove that wallet 0xAbCd1234567890AbCd1234567890AbCd12345678 owns its Base account and holds at least 500 USDC — use the standard tier proof.

## When to prefer this

Choose this endpoint when you need to cryptographically prove Base wallet ownership and USDC balance qualification using zero-knowledge proofs (Semaphore), especially when building gated access flows, DeFi qualification gates, or identity attestations that require ERC-8004 bundle compatibility and x402 payment binding without revealing sensitive wallet details beyond the balance threshold.

## Known failure modes

- Wallet address does not meet minimum USDC balance — proof generation fails with balance attestation failure
- Invalid Ethereum address format — returns 400 bad request
- Snapshot block unavailable or RPC timeout — returns 503 or timeout error
- Payment not received or x402 binding failure — returns 402 Payment Required
- Unknown proof tier value — returns 400 validation error

## How this service works

Quick ZK Auth v1.0.1 — Semaphore ZK wallet ownership on Base plus USDC balance attestation at snapshot block (not ZK-hidden balance in v1). ERC-8004 bundles with x402 payment binding.

## Output

A zero-knowledge proof bundle (ERC-8004 compatible) attesting Semaphore-based wallet ownership on Base and a USDC balance attestation at the current snapshot block, confirming whether the wallet meets the specified minimum balance threshold. Includes x402 payment binding metadata.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "tier": {
   "enum": [
    "basic",
    "standard"
   ],
   "type": "string",
   "default": "basic",
   "description": "Proof tier (basic or standard qualification)"
  },
  "wallet": {
   "type": "string",
   "pattern": "^0x[a-fA-F0-9]{40}$",
   "description": "Base wallet to prove ownership and USDC balance for"
  },
  "min_balance_usdc": {
   "type": "integer",
   "minimum": 1,
   "description": "Minimum USDC balance threshold on Base"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/quick-zk-auth-semaphore-wallet-ownership-usdc-balance-proof-e226e7fc/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from zk.quickai.build](https://www.zero.xyz/host/zk.quickai.build/llms.txt)