# SDKs & Libraries

Chain provides official client libraries for popular languages. SDKs handle authentication, request signing, pagination, error handling, and webhook verification.

## Available SDKs

- **JS**  
  Node.js  
  v2.x — Stable  
  `npm install @chain/node`

- **PY**  
  Python  
  v2.x — Stable  
  `pip install chain-sdk`

- **GO**  
  Go  
  Coming soon

- **RB**  
  Ruby  
  Coming soon

## Installation

### Node.js

```bash
# npm
npm install @chain/node

# yarn
yarn add @chain/node

# pnpm
pnpm add @chain/node
```

## Quick Start

### Node.js

```javascript
import Chain from '@chain/node';

const chain = new Chain('sk_live_...');

// Register a wallet
const wallet = await chain.wallets.create({
  label: 'Treasury',
  address: '0x1a2b3c4d5e6f7890abcdef1234567890abcdef12',
  blockchain: 'ethereum',
  is_primary: true,
});

// Create a funding request
const funding = await chain.funding.create({
  amount: 10000,
  currency: 'USD',
  bank_account_id: 'ba_abc123',
  wallet_id: wallet.id,
});

// Issue a card
const card = await chain.cards.create({
  type: 'virtual',
  cardholder_name: 'Jane Doe',
  business_user_id: 'usr_abc123',
  currency: 'USD',
});

console.log(card.id, card.last_four);
```

## Error Handling

### Node.js

```javascript
import Chain, { ChainError } from '@chain/node';

const chain = new Chain('sk_live_...');

try {
  const payout = await chain.payouts.create({
    amount: 5000,
    currency: 'USD',
    payee_id: 'payee_abc',
    payout_type: 'fiat',
    wallet_id: 'wal_xyz789',
  });
} catch (error) {
  if (error instanceof ChainError) {
    console.error('Status:', error.status);
    console.error('Code:', error.code);
    console.error('Message:', error.message);

if (error.status === 429) {
      // Retry after the specified delay
      const retryAfter = error.headers['retry-after'];
    }
  }
}
```

## Pagination

SDKs provide auto-pagination helpers. Iterate over large collections without manually managing cursors.

### Node.js

```javascript
// Auto-pagination
for await (const wallet of chain.wallets.list({ limit: 10 })) {
  console.log(wallet.id, wallet.label);
}

// Or collect all results
const allWallets = await chain.wallets.list().toArray();
```

## Webhook Helpers

Built-in verification

SDKs include helpers to verify webhook signatures and parse event payloads with full type safety.

### Node.js

```javascript
import { Webhook } from '@chain/node';

const webhook = new Webhook(process.env.CHAIN_WEBHOOK_SECRET);

app.post('/webhooks', (req, res) => {
  const event = webhook.verify(req.body, req.headers);

switch (event.type) {
    case 'funding.completed':
      // event.data is fully typed
      handleFunding(event.data);
      break;
    case 'card.authorization.request':
      handleAuth(event.data);
      break;
  }

res.sendStatus(200);
});
```

**Pax Dollar**  
USDP

**Ripple USD**  
RLUSD

**Dollar**  
USD

**Tether**  
USDT

**Pounds**  
GBP

**Euro**  
Eur