> ## Documentation Index
> Fetch the complete documentation index at: https://docs.midasprotocol.org/llms.txt
> Use this file to discover all available pages before exploring further.

# On-Chain Payments

> Send real USDC on Base L2 with gas paid in USDC — no ETH required

## Overview

MIDAS supports **fully on-chain USDC payments** on Base L2 using [Circle Paymaster](https://developers.circle.com/paymaster). This means agents can transfer real USDC to each other without needing any ETH for gas fees.

Under the hood, MIDAS uses:

* **EIP-7702** smart accounts — the agent's wallet address stays the same
* **Circle Paymaster v0.8** — gas fees are deducted in USDC, not ETH
* **Pimlico bundler** — UserOperations are bundled and submitted to Base
* **Batch calls** — the payment and protocol fees (1.5%) are executed in a single transaction

## Sending an On-Chain Payment

Add `"paymentMethod": "onchain"` to your payment request:

```bash theme={null}
curl -X POST https://api.midasprotocol.org/payments/send \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "toAgentId": "recipient-uuid",
    "amount": 10,
    "currency": "USDC",
    "paymentMethod": "onchain",
    "reason": "Service payment"
  }'
```

### Response

```json theme={null}
{
  "transactionId": "tx-uuid",
  "status": "COMPLETED",
  "amount": "10",
  "currency": "USDC",
  "fees": "0.15",
  "rail": "ONCHAIN",
  "txHash": "0xabc123...",
  "network": "base",
  "gasPayment": "USDC (Circle Paymaster)",
  "explorer": "https://basescan.org/tx/0xabc123...",
  "recipient": { "id": "recipient-uuid", "name": "AgentName" },
  "completedAt": "2026-04-06T23:00:00.000Z"
}
```

Every on-chain transaction is verifiable on [BaseScan](https://basescan.org).

## Using the SDK

```typescript theme={null}
import { MidasClient } from '@midas-protocol/sdk';

const midas = new MidasClient('YOUR_API_KEY');

// Convenience method — always on-chain, always USDC
const result = await midas.payments.sendOnchain({
  toAgentId: 'recipient-uuid',
  amount: 10,
  reason: 'Service payment',
});

console.log(`TX: ${result.explorer}`);

// Or use the generic send with paymentMethod
const result2 = await midas.payments.send({
  toAgentId: 'recipient-uuid',
  amount: 10,
  currency: 'USDC',
  paymentMethod: 'onchain',
});
```

## Using MCP

If your agent uses MIDAS via the MCP server, the `send_payment` tool now accepts `paymentMethod`:

```json theme={null}
{
  "tool": "send_payment",
  "arguments": {
    "toAgentId": "recipient-uuid",
    "amount": 10,
    "currency": "USDC",
    "paymentMethod": "onchain"
  }
}
```

## Payment Methods Comparison

| Method     | Rail             | Gas      | Fees | Speed   |
| ---------- | ---------------- | -------- | ---- | ------- |
| `internal` | DB ledger        | None     | 1.5% | Instant |
| `crypto`   | EOA transfer     | ETH      | 0%   | \~2s    |
| `onchain`  | Circle Paymaster | **USDC** | 1.5% | \~3-5s  |

## Requirements

* Both sender and recipient must have a blockchain wallet (automatically created at registration)
* Sender must have sufficient USDC balance on Base L2 to cover the amount + fees + gas (typically \< 0.01 USDC)
* Currency must be `USDC` — other currencies are not supported for on-chain payments

## How It Works

1. MIDAS decrypts the sender's private key server-side
2. An EIP-7702 smart account is created from the EOA — same address, smart account capabilities
3. An EIP-2612 permit is signed, authorizing Circle Paymaster to deduct gas in USDC
4. A UserOperation is constructed with batch calls: transfer to recipient + fee transfer to treasury
5. The operation is submitted to Base via Pimlico's bundler
6. Circle Paymaster pays gas in ETH and recoups the equivalent in USDC from the sender
7. The transaction is confirmed and recorded in the MIDAS ledger

## Contract Addresses

| Contract                     | Address                                      |
| ---------------------------- | -------------------------------------------- |
| Circle Paymaster v0.8 (Base) | `0x0578cFB241215b77442a541325d6A4E6dFE700Ec` |
| USDC (Base)                  | `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913` |