CardZero Payment Wallet

March 20, 2026 · View on GitHub

Add this to your project's CLAUDE.md to give Claude Code access to CardZero payments.

Setup

Set these environment variables (or add to .env):

CARDZERO_API_URL=https://api.cardzero.ai/v1
CARDZERO_API_KEY=czapi_your_key_here
CARDZERO_WALLET_ID=wallet_your_id_here

CLAUDE.md Snippet

Copy the block below into your project's CLAUDE.md:

CardZero Payment Wallet

Beta — Smart contract audit in progress. Recommended wallet balance: < $100 USDC.

You have a CardZero payment wallet on Base. Use it to make USDC payments.

Config:

  • API URL: ${CARDZERO_API_URL}
  • API Key: ${CARDZERO_API_KEY}
  • Wallet ID: ${CARDZERO_WALLET_ID}

Endpoints:

  1. Check balance: GET /wallets/{walletId}/balance with Authorization: Bearer {API_KEY}
  2. Make payment: POST /payments with body {"to":"0x...","amount":"5.00","currency":"USDC"} — walletId derived from API Key
  3. Payment history: GET /wallets/{walletId}/payments?limit=10 with Authorization: Bearer {API_KEY}
  4. x402 payment: POST /x402/pay with body {"url":"...","maxAmount":"1.00","recipient":"0x...","network":"eip155:8453","asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"}

Rules:

  • Always tell the user the amount, recipient, and reason before paying
  • A 2% fee is deducted separately from the wallet
  • If INSUFFICIENT_BALANCE, suggest the owner add funds
  • If WALLET_FROZEN, the owner has frozen the wallet
  • Use idempotencyKey to prevent duplicate payments on retry

Example — check balance then pay:

curl -H "Authorization: Bearer $CARDZERO_API_KEY" $CARDZERO_API_URL/wallets/$CARDZERO_WALLET_ID/balance
curl -X POST -H "Authorization: Bearer $CARDZERO_API_KEY" -H "Content-Type: application/json" \
  -d '{"to":"0xrecipient","amount":"2.50","currency":"USDC"}' \
  $CARDZERO_API_URL/payments