Arbitrum Supports x402 and MPP For Agentic Finance

Developers now have two new pathways for building agentic payment and settlement flows on Arbitrum. Arbitrum is supported by Coinbase’s hosted x402 facilitator, and Offchain has published arbitrum-mpp, an open-source implementation for making payments over MPP on Arbitrum.

This is an early step toward making Arbitrum a practical home for agentic finance. Agents are starting to call APIs, buy data, execute strategies, and settle transactions with other agents. As that activity grows, they will need fast, programmable settlement and access to the financial infrastructure where capital already moves.

Arbitrum powers the programmable economy: markets, transactions, and business processes that run in software and execute automatically. Agentic finance extends that vision to agents that can request a service, evaluate cost, authorize payment, and continue the workflow without leaving the application context.

The Arbitrum Platform is well suited for that next phase because it combines fast execution, low transaction costs, deep stablecoin liquidity, EVM composability, and one of Ethereum’s most mature DeFi ecosystems. For agents that need to do more than send value from one account to another, that financial depth matters.

x402 support on Arbitrum

Coinbase’s hosted x402 facilitator supports Arbitrum, giving developers a way to build x402-powered services on Arbitrum without standing up their own settlement infrastructure. The facilitator handles key operational pieces of the payment flow, while agents and applications can settle payments on Arbitrum.

x402 makes payment part of the same request and response pattern that software already uses. An agent requesting a paid API endpoint, data product, or service can receive a payment requirement and respond programmatically as part of the interaction.

For agent developers, that makes Arbitrum easier to use for paid digital services, machine-to-machine transactions, and applications where agents need to pay as they act. Developers can start by reviewing Coinbase’s x402 support for Arbitrum, then explore leading x402 use cases on Agentic Market.

MPP support on Arbitrum

Alongside x402 support, Offchain has published arbitrum-mpp, an open-source charge method that lets clients and servers transact over MPP on Arbitrum. This gives developers working code for agent-readable payment flows, including client logic, server logic, authorization, and settlement.

The package ships both halves of the flow as a TypeScript SDK. On the client side, the SDK takes a server’s Challenge and produces a Credential containing a signed payment authorization and the details of what the client is paying for. On the server side, the SDK defines the Challenge, validates incoming credentials, submits the transaction, and confirms that the payment has been settled.

Settlement happens with USDC through a signed transfer authorization. A payment can be authorized offchain and settled onchain without requiring the payer to hold the gas token or send a separate approval first. The implementation can also use any token compatible with Uniswap’s Permit2 contract, which requires a one-time approval for transactions using that token.

The repository includes runnable client and server examples so developers can test the full handshake locally. Read the MPP docs for Arbitrum for full implementation details.

Start building agent payments on Arbitrum

x402 and MPP support are early steps in a broader effort to make Arbitrum a practical home for agentic finance. Upcoming work will focus on clearer developer paths for building, testing, and deploying agentic applications on Arbitrum, including more documentation, example flows, integration guidance, and resources for teams building agent-enabled payment and financial applications.

Agentic finance is still early. The standards, interfaces, and dominant use cases are still forming. But the direction is clear: more economic activity will be initiated and coordinated by agents.

Developers can start experimenting with agentic payment flows on Arbitrum today. Read the MPP docs for Arbitrum or build with x402 through Coinbase’s hosted x402 facilitator.