Developer Interface and SDK

The Q402 SDK allows developers to integrate Sign-to-Pay and policy-aware execution into their own dApps, DAOs, or institutional systems. It provides simple libraries, API endpoints, and policy templates that make gasless and compliant execution accessible to any ecosystem.

SDK Modules

Module	Purpose
@q402/core	Base integration for EIP-712 signature + EIP-7702 authorization
@q402/policy	Hooks to apply or customize compliance logic
@q402/middleware-express	Express.js middleware for instant payment validation
@q402/middleware-hono	Hono-based API middleware
@q402/facilitator	Standalone gas relay and settlement service

Developer Workflow

[ Step 1 ]
Install SDK using npm or yarn.

[ Step 2 ]
Initialize Client with network, token, and policy configuration.

[ Step 3 ]
Generate Signature using @q402/core helper functions.

[ Step 4 ]
Submit Transaction through the Facilitator API.

[ Step 5 ]
Track Status using Audit Tools or the Governance Console.

Integration Benefits

• Rapid Deployment: Integrate in minutes without smart contract rewrites.

• Policy Templates: Prebuilt modules for KYC, treasury, and jurisdictional rules.

• Audit Friendly: Access real-time receipts for accounting or compliance teams.

• Multichain Support: Works with Q402 across all supported networks.

• Composable: Can link directly to Governance Intelligence or RWA modules.

For Institutions

Developers from financial institutions or RWA issuers can use the SDK to create autonomous compliance systems. By combining @q402/policy with Governance Intelligence, they can automate decision-to-execution pipelines while maintaining complete oversight.

The SDK brings enterprise-grade execution logic to Web3 builders and institutional teams alike.