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The X402r SDK provides a complete TypeScript implementation for integrating with the X402r refundable payments protocol. It enables clients, merchants, and arbiters to interact with smart contracts for payment authorization, escrow management, and dispute resolution.

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Packages

The SDK is organized into five packages, each designed for a specific role in the payment ecosystem:

@x402r/core

Shared types, ABIs, network config, deploy utilities, and condition builders.

@x402r/client

SDK for payers to request refunds, freeze payments, and manage escrow.

@x402r/merchant

SDK for merchants to release payments, charge, and handle refunds.

@x402r/arbiter

SDK for arbiters to resolve disputes, manage registry, and automate decisions with AI.

@x402r/helpers

Framework-agnostic helper to mark x402 payment options as refundable with escrow configuration.

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Key Features

Built on viem for fully typed interactions with X402r smart contracts. All ABIs are exported with complete TypeScript types.
Real-time event watching for payment state changes, refund requests, and freeze events across all packages.
Built-in hooks for integrating AI models into dispute resolution workflows with structured evaluation contexts.
deployMarketplaceOperator() deploys all necessary contracts (operator, escrow period, freeze, conditions) in a single call.
On-chain registry for arbiters to register, update metadata, and be discovered by merchants and clients.

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Architecture

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Network Support

NetworkChain IDStatus
Base Sepolia84532Supported
Base Mainnet8453Supported

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Next Steps

Installation

Install the SDK packages in your project.

Core Concepts

Understand the payment lifecycle and key concepts.

Deploy Operator

Deploy a PaymentOperator with one function call.

GitHub

Source code and examples.