Crossmint Server Wallets: Autonomous Payments for AI Agents

We're excited to announce Crossmint Server Wallets support in RelAI Buyer Proxy! This enables autonomous payments without private key management, perfect for AI agents and multi-chain applications.

What are Crossmint Server Wallets?

Crossmint Server Wallets are backend-controlled wallets that can make payments autonomously without user interaction. Unlike traditional custodial wallets, these wallets are managed by your backend using Crossmint's infrastructure.

Key Benefits

🤖 Autonomous Agent Payments

• Autonomous trading bots
• AI-powered services
• Background processing tasks

🔐 No Private Key Management

⛽ Gas Abstraction

🌐 Multi-Chain Support

• Solana with USDC
• Base with USDC
• More chains coming soon

How It Works

Traditional Flow vs Crossmint Server Wallets

1. Generate private keys
Securely store private keys  
Sign transactions with private keys
Manage gas fees manually

1. Create wallet via Crossmint Console
Backend gets admin signer permissions
Make payments via Crossmint API
Crossmint handles gas and signing

Quick Start

1. Create Server Wallet

Go to your RelAI Dashboard → Crossmint Wallets tab:

• Click "+ Solana" to create a Solana wallet
• Click "+ Base" to create a Base wallet
• Each wallet gets a unique address for your user

2. Fund the Wallet

Send USDC to the generated wallet address:

• Solana: Send USDC to the Solana address


• Base: Send USDC to the EVM address

3. Use in API

Add special headers to enable Crossmint payments:

curl "https://api.relai.fi/metered/x?url=https://api.example.com/data" \
  -H "X-API-Key: your-api-key" \
  -H "X-Use-Crossmint: true" \
  -H "X-Preferred-Network: solana"

API Reference

Headers

Balance Check

Check all wallet balances including Crossmint:

curl "https://api.relai.fi/metered/balance" \
  -H "X-API-Key: your-api-key"

Response includes both custodial and Crossmint wallets:

{
  "totalBalance": 1.00,
  "balances": {
    "solana": { "address": "9gAZ...", "balance": 0, "network": "solana" },
    "crossmint_solana": { 
      "address": "GsXzQz2U...", 
      "balance": 1.00, 
      "network": "solana",
      "crossmintChain": "solana",
      "serverManaged": true 
    }
  }
}

Use Cases

AI Agent Integration

// AI agent can pay autonomously
const agentResponse = await fetch('/metered/x?url=https://ai-service.com/process', {
  headers: {
    'X-API-Key': 'user-api-key',
    'X-Use-Crossmint': 'true',
    'X-Preferred-Network': 'solana'
  }
})

Multi-Chain Applications

// Same API key, different networks
const solanaPayment = await apiClient.proxyRequestWithWallet(url, {
  useCrossmint: true,
  preferredNetwork: 'solana'
})
const basePayment = await apiClient.proxyRequestWithWallet(url, {
  useCrossmint: true, 
  preferredNetwork: 'base'
})

Fallback Strategy

// Try Crossmint first, fallback to custodial
try {
  const result = await apiClient.proxyRequestWithWallet(url, {
    useCrossmint: true,
    preferredNetwork: 'solana'
  })
} catch (error) {
  // Fallback to traditional custodial wallets
  const result = await apiClient.proxyRequest(url)
}

Security Considerations

Admin Signer Model

• Your backend has admin permissions over wallets
• Crossmint handles cryptographic operations
• No private keys in your database

Payment Limits

• Use spending limits to control exposure
• Monitor usage through balance API
• Set per-transaction and periodic limits

Audit Trail

• All payments logged with transaction IDs
• Crossmint provides detailed payment history
• Full transparency for compliance

Migration Guide

From Custodial Wallets

1. Keep existing API keys - no changes needed
2. Add Crossmint wallets alongside existing ones
3. Gradually migrate high-autonomy use cases
4. Maintain fallback to custodial wallets

Best Practices

• Use Crossmint for autonomous operations
• Keep custodial wallets for user-controlled operations
• Implement proper spending limits
• Monitor balances regularly
• Set up alerts for unusual activity

What's Next?

We're actively working on:

• More blockchain networks (Polygon, Avalanche, etc.)


• Advanced payment routing


• Enhanced monitoring tools


• Multi-signature support

Get Started Today

1. Create your API key
2. Set up Crossmint wallets
3. Read the documentation