> For the complete documentation index, see [llms.txt](https://quackai.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://quackai.gitbook.io/docs/q402-execution-layer/compliance.md).

# 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.