# Monad charge \[One-time payments on Monad] The Monad implementation of the [charge](/intents/charge) intent. The server issues a charge challenge describing the expected amount, currency, and recipient. The client either broadcasts an ERC-20 `transfer` and returns the transaction hash (**push** mode), or signs an ERC-3009 `transferWithAuthorization` for the server to broadcast (**pull** mode). The server verifies the transfer on-chain and returns the resource with a receipt. This method is best for fixed-price API calls, digital goods, and payments that should settle directly on Monad. ## Server Use `monad.charge` to gate any endpoint behind a one-time ERC-20 payment. The method handles Challenge generation, Credential verification, on-chain settlement, and Receipt creation. ```ts import { Mppx } from "mppx/server"; import { monad } from "@monad-crypto/mpp/server"; const mppx = Mppx.create({ methods: [monad()], }); export async function handler(request: Request) { const result = await mppx.charge({ amount: "0.1", currency: "0x754704Bc059F8C67012fEd69BC8A327a5aafb603", // USDC recipient: "0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266", })(request); if (result.status === 402) return result.challenge; return result.withReceipt(Response.json({ data: "..." })); } ``` ### With pull mode (ERC-3009) To accept pull mode credentials, provide an `account` so the server can broadcast `transferWithAuthorization` and pay gas: ```ts import { Mppx } from "mppx/server"; import { monad } from "@monad-crypto/mpp/server"; import { privateKeyToAccount } from "viem/accounts"; const account = privateKeyToAccount(process.env.SERVER_PRIVATE_KEY as `0x${string}`); const mppx = Mppx.create({ methods: [monad.charge({ account, // [!code hl] })], }); ``` ## Client Use `monad.charge` with `Mppx.create` to automatically handle `402` responses. The client parses the Challenge, creates a credential (either a signed transfer or an ERC-3009 authorization), and retries with the Credential. ```ts import { Mppx } from "mppx/client"; import { monad } from "@monad-crypto/mpp/client"; import { privateKeyToAccount } from "viem/accounts"; const account = privateKeyToAccount("0xabc…123"); const mppx = Mppx.create({ methods: [monad.charge({ account })], }); const response = await mppx.fetch("https://api.example.com/resource"); ``` ## Settlement modes Monad charge supports two settlement modes: * **Push** — the client broadcasts an ERC-20 `transfer(recipient, amount)` transaction on-chain and includes the transaction hash in the credential. The server verifies the transfer by reading `Transfer` event logs. * **Pull** — the client signs an ERC-3009 `transferWithAuthorization` off-chain. The server broadcasts the authorization on-chain via `transferWithAuthorization`, paying the gas. The server account does not need to match the recipient address.