> ## Documentation Index
> Fetch the complete documentation index at: https://docs-openpay.nipuntheekshana.com/llms.txt
> Use this file to discover all available pages before exploring further.

# SDK Overview

> Official SDKs for integrating Open Pay into any application

# SDKs

Open Pay provides official SDKs for five languages plus a CLI tool. Every SDK handles HMAC-SHA256 request signing automatically, so you never have to compute signatures manually.

<CardGroup cols={3}>
  <Card title="TypeScript" icon="js" href="/sdks/typescript">
    `@openpay/sdk` for Node.js and edge runtimes
  </Card>

  <Card title="Go" icon="golang" href="/sdks/go">
    `openlankapay-go-sdk` for backend services
  </Card>

  <Card title="Python" icon="python" href="/sdks/python">
    `openpay-sdk` with async httpx support
  </Card>

  <Card title="PHP" icon="php" href="/sdks/php">
    `openpay/sdk` via Composer
  </Card>

  <Card title="Java" icon="java" href="/sdks/java">
    `com.openpay:openpay-sdk` for JVM applications
  </Card>

  <Card title="CLI" icon="terminal" href="/sdks/cli">
    `openpay` command-line tool
  </Card>
</CardGroup>

## Common Features

All SDKs share the same capabilities:

| Feature                  | Description                                                       |
| ------------------------ | ----------------------------------------------------------------- |
| **Create Payments**      | Generate payment requests with amount, currency, and metadata     |
| **Checkout Sessions**    | Create hosted checkout pages with success/cancel URLs             |
| **Webhook Verification** | Verify ED25519-signed webhook payloads                            |
| **HMAC Authentication**  | Automatic request signing with your API key and secret            |
| **Error Handling**       | Typed errors with status codes and descriptive messages           |
| **Retry Logic**          | Automatic retries with exponential backoff for transient failures |

## Authentication

Every SDK uses HMAC-SHA256 to sign requests. You provide your API key (public identifier) and API secret (signing key), and the SDK handles the rest.

The signature is computed as:

```
message = timestamp + method + path + body
signing_key = SHA256(api_secret)
signature = HMAC-SHA256(message, signing_key)
```

These headers are sent with each request:

| Header        | Value                          |
| ------------- | ------------------------------ |
| `x-api-key`   | Your API key (`ak_live_xxx`)   |
| `x-timestamp` | Unix timestamp in milliseconds |
| `x-signature` | HMAC-SHA256 hex digest         |

<Info>
  Get your API key and secret from the [Merchant Portal](https://olp-merchant.nipuntheekshana.com/integrations) under **Integrations**.
</Info>

## Quick Comparison

<Tabs>
  <Tab title="TypeScript">
    ```typescript theme={null}
    import { OpenPay } from "@openpay/sdk";

    const client = new OpenPay({
      apiKey: process.env.OPENPAY_API_KEY!,
      apiSecret: process.env.OPENPAY_API_SECRET!,
    });
    ```
  </Tab>

  <Tab title="Go">
    ```go theme={null}
    client := openpay.NewClient(
        os.Getenv("OPENPAY_API_KEY"),
        os.Getenv("OPENPAY_API_SECRET"),
    )
    ```
  </Tab>

  <Tab title="Python">
    ```python theme={null}
    from openpay import OpenPayClient

    client = OpenPayClient(
        api_key=os.environ["OPENPAY_API_KEY"],
        api_secret=os.environ["OPENPAY_API_SECRET"],
    )
    ```
  </Tab>

  <Tab title="PHP">
    ```php theme={null}
    $client = new \OpenPay\OpenPayClient(
        apiKey: getenv('OPENPAY_API_KEY'),
        apiSecret: getenv('OPENPAY_API_SECRET'),
    );
    ```
  </Tab>

  <Tab title="Java">
    ```java theme={null}
    OpenPayClient client = OpenPayClient.builder()
        .apiKey(System.getenv("OPENPAY_API_KEY"))
        .apiSecret(System.getenv("OPENPAY_API_SECRET"))
        .build();
    ```
  </Tab>
</Tabs>

## API Base URL

All SDKs default to the production API:

```
https://olp-api.nipuntheekshana.com
```

You can override this by passing a `baseUrl` option during client initialization if you are targeting a different environment.