> For the complete documentation index, see [llms.txt](https://docs.opinion.trade/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.opinion.trade/developer-guide/opinion-clob-typescript-sdk/core-concepts/client.md).

# Client

The `Client` class is the main interface to the Opinion prediction market infrastructure. It provides methods for market data queries, trading, position management, and blockchain interactions.

## Initialization

{% code title="example.ts" %}

```typescript
import 'dotenv/config';
import { Client, CHAIN_ID_BNB_MAINNET, DEFAULT_API_HOST } from '@opinion-labs/opinion-clob-sdk';

const client = new Client({
  host: DEFAULT_API_HOST,
  apiKey: process.env.API_KEY!,
  chainId: CHAIN_ID_BNB_MAINNET,
  rpcUrl: process.env.RPC_URL!,
  privateKey: process.env.PRIVATE_KEY! as `0x${string}`,
  multiSigAddress: process.env.MULTI_SIG_ADDRESS! as `0x${string}`,
});
```

{% endcode %}

{% hint style="warning" %}
Security: Never hardcode API keys or private keys. Always load from environment variables.
{% endhint %}

## Method Categories

| Category         | Description                         | Gas Required       |
| ---------------- | ----------------------------------- | ------------------ |
| Market Data      | Query markets, orderbooks, prices   | No                 |
| Trading          | Place and cancel orders             | No (gas-free CLOB) |
| User Data        | Query positions, balances, trades   | No                 |
| Token Operations | split, merge, redeem, enableTrading | Yes (BNB)          |

## Response Format

All API methods return a consistent response wrapper:

{% code title="example.ts" %}

```typescript
const response = await client.getMarkets();

// Response structure
response.errno    // 0 = success
response.errmsg   // Error message (empty on success)
response.result   // Data payload
```

{% endcode %}

The `ApiResponse<T>` type is defined as:

{% code title="types.ts" %}

```typescript
interface ApiResponse<T> {
  errno: number;
  errmsg: string;
  result: T;
}
```

{% endcode %}

## Caching

The Client implements built-in caching for frequently accessed data:

| Cache          | Default TTL      | Recommendation                   |
| -------------- | ---------------- | -------------------------------- |
| Quote Tokens   | 3600s (1 hour)   | Rarely changes, keep high        |
| Market Data    | 300s (5 minutes) | Balance freshness vs performance |
| Enable Trading | 3600s (1 hour)   | Approvals rarely change          |

Cache TTLs can be configured during initialization:

{% code title="example.ts" %}

```typescript
const client = new Client({
  host: DEFAULT_API_HOST,
  apiKey: process.env.API_KEY!,
  chainId: CHAIN_ID_BNB_MAINNET,
  rpcUrl: process.env.RPC_URL!,
  privateKey: process.env.PRIVATE_KEY! as `0x${string}`,
  multiSigAddress: process.env.MULTI_SIG_ADDRESS! as `0x${string}`,
  quoteTokensCacheTtl: 7200,  // 2 hours
  marketCacheTtl: 120,         // 2 minutes
  enableTradingCheckInterval: 1800, // 30 minutes
});
```

{% endcode %}

Bypass cache for individual calls:

{% code title="example.ts" %}

```typescript
// Bypass cache
const tokens = await client.getQuoteTokens(false);
const market = await client.getMarket(123, false);
```

{% endcode %}

## Best Practices

{% stepper %}
{% step %}

### Single Instance

Create one Client for your application; connection pooling is automatic.
{% endstep %}

{% step %}

### Error Checking

Always check `errno` before accessing `result`.
{% endstep %}

{% step %}

### Cache Tuning

Adjust cache TTLs based on your use case.
{% endstep %}

{% step %}

### Connectivity Verification

Test with `getQuoteTokens()` before trading.
{% endstep %}

{% step %}

### Async/Await

All Client methods are async; always use `await` when calling them.
{% endstep %}
{% endstepper %}


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