### Set Up Node.js Project and Install Dependencies

Source: https://developers.circle.com/xreserve/tutorials/deposit-usdc-on-ethereum-for-usdcx-on-canton

This snippet sets up a new Node.js project directory, initializes it with npm, and installs essential libraries like viem for blockchain interaction and dotenv for environment variable management.

```shell
# Set up your directory and initialize the project
mkdir deposit-usdc-into-xreserve-for-usdcx-on-canton-quickstart
cd deposit-usdc-into-xreserve-for-usdcx-on-canton-quickstart
npm init -y

# Install tools and dependencies
npm install viem dotenv
```

--------------------------------

### Install Modular Wallets Web SDK using npm

Source: https://developers.circle.com/wallets/modular/create-a-wallet-and-send-gasless-txn

This command installs the core SDK for modular wallets on the web. Ensure you have Node.js and npm (or yarn) installed.

```bash
npm install @circle-fin/modular-wallets-core
```

--------------------------------

### Install Aptos SDK and Wallet Adapters

Source: https://developers.circle.com/stablecoins/quickstart-setup-transfer-usdc-aptos

Installs the necessary Aptos SDK and wallet adapter packages required for interacting with the Aptos blockchain and managing user wallets within the application.

```shell
npm install @aptos-labs/ts-sdk @aptos-labs/wallet-adapter-ant-design @aptos-labs/wallet-adapter-react
```

--------------------------------

### Install Viem and Dotenv Dependencies

Source: https://developers.circle.com/stablecoins/quickstart-setup-transfer-usdc-sei

Installs the necessary JavaScript libraries for interacting with blockchains (Viem) and managing environment variables (dotenv).

```shell
npm install viem dotenv
```

--------------------------------

### Initialize Project and Install Dependencies (Shell)

Source: https://developers.circle.com/stablecoins/quickstart-transfer-10-usdc-on-chain

Commands to create a new project directory, initialize an npm project, and install essential React, Vite, and TypeScript dependencies for building a React app.

```shell
mkdir usdc-transfer-app
cd usdc-transfer-app
npm init -y
npm install react@^18.2.0 \
react-dom@^18.2.0 \
@types/react@^18.0.27 \
@types/react-dom@^18.0.10 \
@vitejs/plugin-react@^3.1.0 \
typescript@^5.0.3 \
vite@^4.4.5
```

--------------------------------

### Install Dependencies for Sui Integration

Source: https://developers.circle.com/stablecoins/quickstart-setup-transfer-usdc-sui

Installs essential libraries for interacting with the Sui blockchain and managing wallet connections within a React application. These include SDKs for Sui, wallet integration, and query management.

```shell
npm install @mysten/dapp-kit @mysten/sui @mysten/wallet-kit @tanstack/react-query

```

--------------------------------

### Install Dependencies with npm

Source: https://developers.circle.com/stablecoins/quickstart-setup-transfer-usdc-ink

Initializes a new Node.js project, sets the module type to ES module, and installs the necessary Viem and dotenv libraries. These are fundamental for interacting with blockchain and managing environment variables.

```shell
npm init -y
npm pkg set type=module
npm install viem dotenv

```

--------------------------------

### Install Viem Library

Source: https://developers.circle.com/stablecoins/quickstart-transfer-10-eurc-on-chain

Installs the viem library, a lightweight, fast, and type-safe Ethereum utilities library for TypeScript and JavaScript. It's crucial for interacting with the Ethereum blockchain.

```shell
npm install viem
```

--------------------------------

### Install Circle Contracts Python SDK

Source: https://developers.circle.com/sdks/contracts-python-sdk

Installs the Circle Smart Contract Platform SDK using pip. Ensure you have Python installed and an active Circle Developer Account.

```bash
pip install circle-smart-contract-platform
```

--------------------------------

### Set up Development Environment with npm

Source: https://developers.circle.com/gateway/quickstarts/unified-balance

Initializes a new Node.js project, sets the package type to module, and installs necessary dependencies like viem and dotenv. This is the first step in setting up the project environment.

```shell
mkdir unified-balance-quickstart && cd unified-balance-quickstart
npm init -y
npm pkg set type="module"
npm install --save viem dotenv
```

--------------------------------

### Main Application Component Setup

Source: https://developers.circle.com/stablecoins/quickstart-setup-transfer-usdc-aptos

This component serves as the main entry point for the application, wrapping the core UI logic (`HomeContent`) with necessary providers. It ensures that state management and wallet connection functionalities are available throughout the application tree. The component includes basic error handling for the provider.

```typescript
export default function Home() {
  return (
    <AptosWalletProvider>
      <HomeContent />
    </AptosWalletProvider>
  );
}
```

--------------------------------

### Install User-Controlled Wallets Python SDK

Source: https://developers.circle.com/sdks/user-controlled-wallets-python-sdk

Installs the Circle User-Controlled Wallets Python SDK using pip. Ensure you have Python installed and are using a virtual environment for best practices.

```bash
pip install circle-user-controlled-wallets
```

--------------------------------

### Testing Authentication

Source: https://developers.circle.com/circle-mint/authentication

Verify your API key setup by using the 'get configuration info' API endpoint. This example uses cURL to make a GET request to the sandbox configuration endpoint.

```APIDOC
## GET /v1/configuration

### Description
Tests the authentication by retrieving configuration information. This is a good way to verify if your API key is correctly set up.

### Method
GET

### Endpoint
`https://api-sandbox.circle.com/v1/configuration`

### Parameters
#### Headers
- **Accept** (string) - Required - `application/json`
- **Authorization** (string) - Required - `Bearer YOUR_API_KEY`

### Request Example
```bash
# Replace ${YOUR_API_KEY} with your API key
curl -H 'Accept: application/json' \
     -H "Authorization: Bearer ${YOUR_API_KEY}" \
     -X GET --url https://api-sandbox.circle.com/v1/configuration
```

### Response
#### Success Response (200)
- **data** (object) - Contains configuration details.
  - **payments** (object)
    - **masterWalletId** (string) - The master wallet ID.

#### Response Example
```json
{
  "data": {
    "payments": {
      "masterWalletId": "1234567890"
    }
  }
}
```

#### Error Response (401)
- **code** (integer) - The error code.
- **message** (string) - A description of the error.

#### Response Example
```json
{
  "code": 401,
  "message": "Malformed authorization. Are the credentials properly encoded?"
}
```
```

--------------------------------

### Install Node.js SDK for Developer-Controlled Wallets

Source: https://developers.circle.com/sdks/developer-controlled-wallets-nodejs-sdk

Install the developer-controlled wallets SDK using npm or yarn. This command adds the necessary package to your project for interacting with Circle's wallet APIs. Ensure you have Node.js and npm installed.

```bash
npm install @circle-fin/developer-controlled-wallets --save
```

```bash
yarn add @circle-fin/developer-controlled-wallets
```

--------------------------------

### Initialize Project with npm

Source: https://developers.circle.com/stablecoins/quickstart-setup-transfer-usdc-sei

Initializes a new project directory and sets up npm for module usage. It creates a package.json file and configures it to use ES modules.

```shell
mkdir usdc-sei-script
cd usdc-sei-script
npm init -y
npm pkg set type=module
```

--------------------------------

### Example SNS Notification Response

Source: https://developers.circle.com/circle-mint/circle-apis-notifications-quickstart

This example shows the plain text format of a response received from Amazon Simple Notification Service (SNS) when subscribing to Circle notifications. It includes essential details for verifying the subscription and signing the request.

```plaintext
{
  "Type": "SubscriptionConfirmation",
  "MessageId": "43f97f6e1865505e2f29f79a62f89e18f97e03a0dd5d982a7578c8d6e21154163f2d6aae523cff25557f9bc21b2503d413006",
  "Timestamp": "2020-04-11T20:50:16.324Z",
  "SignatureVersion": "1",
  "Signature": "kBr9z/ysQrr0ldowHY4lThkOA+dwyjcsyx7NwkbTkgEKG4N61BSSEA+43aYQEB/Ml09hclybvyjyRKWYOjaxQgbUXWmyWrCQ7vY93WYhuGvOqZxAMPiDiILxLs6/KtOxneKVvzfpK4abLrYyTTA+z/dQ52h9L8eoiSKSW81e4clfYBTJkGmuAPKFC08FvEAVT89VikPp68mBf4CctPv3Em0b4J1VvDhAB21B2LekgUmwUE0aE7fUbsF3XsKGQd/fDshLOJasQEuXSqdB5X7LITBA8r24FY+wCjwm8oR3VI9IMy21fUC6wMgoFIVZHW1KxzpEkMCSe7R1ySdNIru8SQ==",
  "SigningCertURL": "https://sns.us-west-2.amazonaws.com/SimpleNotificationService-a86cb10b4e1f29c941702d737128f7b6.pem"
}
```

--------------------------------

### Project Setup with Next.js

Source: https://developers.circle.com/stablecoins/quickstart-setup-transfer-usdc-sui

Initializes a new Next.js project with TypeScript, ESLint, and Tailwind CSS. This command sets up the basic structure for the web application.

```shell
npx create-next-app@latest usdc-transfer-app

```

--------------------------------

### Test API Key Authentication using curl

Source: https://developers.circle.com/w3s/keys

This `curl` command example shows how to test your API key setup by making a GET request to retrieve wallets from the Circle API. It includes the necessary headers for authentication and specifies the endpoint.

```shell
curl --request GET \
--url https://api.circle.com/v1/w3s/wallets \
--header 'accept: application/json' \
--header 'authorization: Bearer '
```

--------------------------------

### List Developer-Controlled Wallets - cURL Request

Source: https://developers.circle.com/wallets/dev-controlled/receive-an-inbound-transfer

This example shows how to list developer-controlled wallets using a cURL command. It demonstrates the HTTP GET request to the appropriate API endpoint. The response includes a list of wallets with their details, such as address and state.

```bash
curl "https://api.circle.com/v1/wallets" \
     -H "Authorization: Bearer YOUR_API_KEY" \
     -H "Content-Type: application/json"
```

--------------------------------

### Navigate to Project Directory

Source: https://developers.circle.com/stablecoins/quickstart-setup-transfer-usdc-aptos

Change the current directory to the newly created Next.js project directory to begin installing dependencies and modifying files.

```shell
cd usdc-transfer-app
```

--------------------------------

### Get USDC Transfer Fees Response Example (JSON)

Source: https://developers.circle.com/api-reference/cctp/all/get-burn-usdc-fees

Example JSON response for the 'Get USDC Transfer Fees' API call, detailing `finalityThreshold` and `minimumFee` in basis points for different transfer types.

```json
[
  {
    "finalityThreshold": 1000,
    "minimumFee": 1
  },
  {
    "finalityThreshold": 2000,
    "minimumFee": 0
  }
]
```

--------------------------------

### Set up Wallet Client (Viem)

Source: https://developers.circle.com/stablecoins/quickstart-transfer-10-eurc-on-chain

Configures a wallet client using viem to interact with user accounts and sign transactions. This example specifically sets it up to connect with MetaMask in the browser.

```typescript
import { createWalletClient, custom } from "viem";
import { sepolia } from "viem/chains";

const walletClient = createWalletClient({
  chain: sepolia,
  transport: custom(window.ethereum!),
});
```

--------------------------------

### Challenge Initialization Notification Example

Source: https://developers.circle.com/wallets/webhook-notifications

This is an example of a notification message received when a challenge payment is initiated.

```APIDOC
## Sample Challenge Notification

This JSON object represents a notification received upon successful initiation of a challenge payment.

```json
{
  "subscriptionId": "a68cd974-d209-46cd-8dbf-b7a081fbd627",
  "notificationId": "eaa4a4fe-24b8-4329-a4c6-6dfd557dbcb2",
  "notificationType": "challenges.initialize",
  "notification": {
    "id": "9c0a1991-735a-5140-8996-7b95720c5e55",
    "userId": "2a054cd1-3124-4aa7-b1f0-86c4a4df995c",
    "type": "INITIALIZE",
    "status": "COMPLETE",
    "correlationIds": ["01890792-a199-77bc-b005-b229f81824fa"],
    "errorCode": 0,
    "errorMessage": ""
  },
  "timestamp": "2023-06-29T14:33:17.785131449Z",
  "version": 2
}
```
```

--------------------------------

### Webhook Signature Verification Example (Python)

Source: https://developers.circle.com/wallets/webhook-notifications

Example code demonstrating how to verify the `X-Circle-Signature` header using the retrieved public key and the webhook payload.

```APIDOC
## Verify Digital Signature

### Description
This section details how to verify the digital signature of incoming webhook notifications to ensure their integrity and authenticity. It involves retrieving the public key using the `X-Circle-Key-Id` header and then using it to validate the `X-Circle-Signature` against the payload.

### Headers
- **X-Circle-Signature** (string) - The digital signature of the webhook payload.
- **X-Circle-Key-Id** (string) - The UUID of the public key used for signing.

### Request
1. Use the `X-Circle-Key-Id` from the request headers to call the `GET /v2/notifications/publicKey/{keyId}` endpoint to retrieve the public key and algorithm.
2. Use the retrieved public key and algorithm to verify the `X-Circle-Signature` against the webhook payload.

### Request Example (Python)
```python
import base64
from cryptography.exceptions import InvalidSignature
from cryptography.hazmat.primitives import hashes, serialization
from cryptography.hazmat.primitives.asymmetric import ec

# Assume public_key_base64 and signature_base64 are obtained from previous steps
# Assume message is the raw webhook payload string

# --- Obtain Public Key (example, should be cached) ---
public_key_base64 = "MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAESl76SZPBJemW0mJNN4KTvYkLT8bOT4UGhFhzNk3fJqf6iuPlLQLq533FelXwczJbjg2U1PHTvQTK7qOQnDL2Tg=="
public_key_bytes = base64.b64decode(public_key_base64)
public_key = serialization.load_der_public_key(public_key_bytes)

# --- Obtain Signature and Message ---
# Example values, replace with actual received data
signature_base64 = "MEQCIBlJPX7t0FDOcozsRK6qIQwik5Fq6mhAtCSSgIB/yQO7AiB9U5lVpdufKvPhk3cz4TH2f5MP7ArnmPRBmhPztpsIFQ=="
signature_bytes = base64.b64decode(signature_base64)

message = "{\"subscriptionId\":\"00000000-0000-0000-0000-000000000000\",\"notificationId\":\"00000000-0000-0000-0000-000000000000\",\"notificationType\":\"webhooks.test\",\"notification\":{\"hello\":\"world\"},\"timestamp\":\"2024-01-26T18:22:19.779834211Z\",\"version\":2}"
message_bytes = message.encode(encoding="utf-8")

# --- Verify Signature ---
try:
    public_key.verify(
        signature_bytes,
        message_bytes,
        ec.ECDSA(hashes.SHA256()),
    )
    print("Signature is valid.")
except InvalidSignature:
    print("Signature is invalid.")
```
```

--------------------------------

### Start Development Server Command

Source: https://developers.circle.com/stablecoins/quickstart-setup-transfer-usdc-aptos

This command initiates the development server for the project. It's typically executed from the project's root directory using a package manager like npm or yarn. The server allows for live reloading and efficient development workflows.

```shell
npm run dev
```

--------------------------------

### Get a Recipient - Circle API Response Example

Source: https://developers.circle.com/api-reference/circle-mint/payouts/get-address-book-recipient

This is an example JSON response for successfully retrieving a recipient's information from the Circle Crypto Address Book API. It includes details such as the recipient's ID, blockchain, address, metadata (nickname, email, bns), status, and timestamps.

```json
{
  "data": {
    "id": "b8627ae8-732b-4d25-b947-1df8f4007a29",
    "chain": "ALGO",
    "address": "0x8381470ED67C3802402dbbFa0058E8871F017A6F",
    "addressTag": "123456789",
    "metadata": {
      "nickname": "sample nickname",
      "email": "satoshi@circle.com",
      "bns": "sample.circle"
    },
    "status": "pending",
    "createDate": "2020-04-10T02:13:30.000Z",
    "updateDate": "2020-04-10T02:13:30.000Z"
  }
}
```

--------------------------------

### Get Event Monitors Response Example (JSON)

Source: https://developers.circle.com/api-reference/contracts/smart-contract-platform/get-event-monitors

Example JSON response for the 'Get Event Monitors' API endpoint. It contains a 'data' object with an 'eventMonitors' array, where each element represents a configured event monitor including its ID, blockchain, contract address, event signature, and status.

```json
{
  "data": {
    "eventMonitors": [
      {
        "id": "e3c998a5-bdf1-4f3e-812f-24da238c0fff",
        "blockchain": "ETH",
        "contractAddress": "0x6bc50ff08414717f000431558c0b585332c2a53d",
        "eventSignature": "Transfer(address indexed from, address indexed to, uint256 value)",
        "eventSignatureHash": "0xd3d3dd4b1fd3e53f94deb24e763485b4c925345c5abfa9ad529c67aa55a3b784",
        "isEnabled": true,
        "createDate": "2023-01-01T12:00:00Z",
        "updateDate": "2023-01-10T15:30:00Z"
      }
    ]
  }
}
```

--------------------------------

### Initialize Viem Clients and Contracts (JavaScript)

Source: https://developers.circle.com/gateway/quickstarts/unified-balance

Sets up Viem clients and contract instances for interacting with the Gateway protocol on different testnets. It requires a PRIVATE_KEY in the environment variables for account creation and uses specific RPC URLs for Base Sepolia.

```javascript
import "dotenv/config";
import { createPublicClient, getContract, http, erc20Abi } from "viem";
import { privateKeyToAccount } from "viem/accounts";
import * as chains from "viem/chains";
import { GatewayClient } from "./gateway-client.js";
import { gatewayWalletAbi, gatewayMinterAbi } from "./abis.js";

// Addresses that are needed across networks
const gatewayWalletAddress = "0x0077777d7EBA4688BDeF3E311b846F25870A19B9";
const gatewayMinterAddress = "0x0022222ABE238Cc2C7Bb1f21003F0a260052475B";
const usdcAddresses = {
  sepolia: "0x1c7D4B196Cb0C7B01d743Fbc6116a902379C7238",
  baseSepolia: "0x036CbD53842c5426634e7929541eC2318f3dCF7e",
  avalancheFuji: "0x5425890298aed601595a70ab815c96711a31bc65",
};

// Sets up a client and contracts for the given chain and account
function setup(chainName, account) {
  const chain = chains[chainName];
  const client = createPublicClient({
    chain,
    account,
    // Use the flashblocks-aware RPC for Base Sepolia, otherwise use the default RPC
    transport: chainName === "baseSepolia" ? http("https://sepolia-preconf.base.org") : http(),
  });

  return {
    client,
    name: chain.name,
    domain: GatewayClient.DOMAINS[chainName],
    currency: chain.nativeCurrency.symbol,
    usdc: getContract({
      address: usdcAddresses[chainName],
      abi: erc20Abi,
      client,
    }),
    gatewayWallet: getContract({
      address: gatewayWalletAddress,
      abi: gatewayWalletAbi,
      client,
    }),
    gatewayMinter: getContract({
      address: gatewayMinterAddress,
      abi: gatewayMinterAbi,
      client,
    }),
  };
}

// Create an account from the private key set in .env
export const account = privateKeyToAccount(process.env.PRIVATE_KEY);
console.log(`Using account: ${account.address}`);

// Set up clients and contracts for each chain
export const ethereum = setup("sepolia", account);
export const base = setup("baseSepolia", account);
export const avalanche = setup("avalancheFuji", account);

```

--------------------------------

### Create and Initialize Project Directory (Shell)

Source: https://developers.circle.com/stablecoins/quickstart-setup-usdc-trustline-xrpl

This command creates a new directory for the XRPL USDC trustline project and initializes it with npm. This is the first step in setting up the project environment.

```shell
mkdir xrpl-usdc-trustline
cd xrpl-usdc-trustline
npm init -y
```

--------------------------------

### CCTP V2 Get Messages and Attestations Response Example (JSON)

Source: https://developers.circle.com/api-reference/cctp/all/get-messages-v2

An example JSON response for the 'Get messages and attestations' API endpoint. It details a completed transaction with message hash, event nonce, attestation signature, and decoded message parameters including sender, recipient, and message body. The `decodedMessageBody` further breaks down the transfer details.

```json
{
  "messages": [
    {
      "message": "0x00000000000000050000000300000000000194c2a65fc943419a5ad590042fd67c9791fd015acf53a54cc823edb8ff81b9ed722e00000000000000000000000019330d10d9cc8751218eaf51e8885d058642e08a000000000000000000000000fc05ad74c6fe2e7046e091d6ad4f660d2a15976200000000c6fa7af3bedbad3a3d65f36aabc97431b1bbe4c2d2f6e0e47ca60203452f5d610000000000000000000000002d475f4746419c83be23056309a8e2ac33b30e3b0000000000000000000000000000000000000000000000000000000002b67df0feae5e08f5e6bf04d8c1de7dada9235c56996f4420b14371d6c6f3ddd2f2da78",
      "eventNonce": "9682",
      "attestation": "0x6edd90f4a0ad0212fd9fbbd5058a25aa8ee10ce77e4fc143567bbe73fb6e164f384a3e14d350c8a4fc50b781177297e03c16b304e8d7656391df0f59a75a271f1b",
      "decodedMessage": {
        "sourceDomain": "7",
        "destinationDomain": "5",
        "nonce": "569",
        "sender": "0xca9142d0b9804ef5e239d3bc1c7aa0d1c74e7350",
        "recipient": "0xb7317b4EFEa194a22bEB42506065D3772C2E95EF",
        "destinationCaller": "0xf2Edb1Ad445C6abb1260049AcDDCA9E84D7D8aaA",
        "messageBody": "0x00000000000000050000000300000000000194c2a65fc943419a5ad590042fd67c9791fd015acf53a54cc823edb8ff81b9ed722e00000000000000000000000019330d10d9cc8751218eaf51e8885d058642e08a000000000000000000000000fc05ad74c6fe2e7046e091d6ad4f660d2a15976200000000c6fa7af3bedbad3a3d65f36aabc97431b1bbe4c2d2f6e0e47ca60203452f5d610000000000000000000000002d475f4746419c83be23056309a8e2ac33b30e3b0000000000000000000000000000000000000000000000000000000002b67df0feae5e08f5e6bf04d8c1de7dada9235c56996f4420b14371d6c6f3ddd2f2da78",
        "decodedMessageBody": {
          "burnToken": "0x4Bc078D75390C0f5CCc3e7f59Ae2159557C5eb85",
          "mintRecipient": "0xb7317b4EFEa194a22bEB42506065D3772C2E95EF",
          "amount": "5000",
          "messageSender": "0xca9142d0b9804ef5e239d3bc1c7aa0d1c74e7350"
        }
      },
      "cctpVersion": 2,
      "status": "complete"
    }
  ]
}
```

--------------------------------

### Initialize Project and Install Dependencies (Shell)

Source: https://developers.circle.com/paymaster/pay-gas-fees-usdc

Sets up a new Node.js project, configures it for ES modules, and installs necessary dependencies: viem for blockchain interaction and dotenv for environment variable management.

```shell
npm init
npm pkg set type="module"
npm install --save viem dotenv

```

--------------------------------

### Set up Wallet Client with viem (TypeScript)

Source: https://developers.circle.com/stablecoins/quickstart-transfer-10-usdc-on-chain

Configures a wallet client using viem to interact with Ethereum accounts for sending transactions and signing messages on the Sepolia network.

```typescript
import { createWalletClient } from "viem";
import { sepolia } from "viem/chains";

const walletClient = createWalletClient({
  chain: sepolia,
  transport: custom(window.ethereum!),
});
```