# ePOS SDK Overview

The Teya Unified SDK enables ePOS applications to integrate with Teya payment card machines on different frameworks using a plug-and-play approach. It removes the complexity of handling authentication, token refresh, and payment flow logic so that partners can focus on their business use cases.

## What Is Poslink?

PosLink is a cloud-based integration where your ePOS application communicates with a Teya payment card machine over the cloud. The SDK manages authentication using OAuth 2.0, handles token refresh automatically, and provides prebuilt payment UI screens out of the box.

## When to use Poslink?

Choose PosLink when your ePOS app runs on a tablet, PC, or Android device that is physically separate from the payment card machine. For example:

- A Windows-based POS system in a retail store that connects to a countertop card machine.
- An Android tablet POS app that pairs with a wireless Teya payment card machine.

```admonition
icon: fas fa-layer-group
title: Running your ePOS on the card machine itself?
content: If your ePOS application and the Teya payment app run on the same Android device, use the All-In-One integration instead.
link: /epos-sdk/all-in-one/overview
```

## Key Benefits

**Managed Authentication**  
The SDK handles OAuth client authentication and token refresh automatically.

**Prebuilt Payment UI**  
Includes ready-to-use payment screens for consistent UX without extra development.

**Cross-Platform Support**  
Works on both Android and Windows, with iOS support planned.

**Minimal Setup**  
Only requires configuring the Client ID and Client Secret obtained from the [Teya Developer Portal](/epos-sdk/setup-and-authentication#1-get-your-credentials) and start development.

![PosLink Integration Diagram](/epos-sdk/images/poslink-integration.png)

## Get Started

The checklist below helps developers get started with PosLink integration quickly and correctly.

<iframe width="560" height="315" src="https://www.youtube.com/embed/LeYli3YTPHE?si=3kfyok5jvPxXhEyM" title="YouTube video player" frameborder="0" allow="accelerometer; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>

## Integration Checklist

### 1. Get your credentials

See [Setup & Authentication](/epos-sdk/setup-and-authentication#1-get-your-credentials) for how to access the Teya Developer Portal and create an OAuth application to obtain your **Client ID** and **Client Secret**.

```admonition
icon: fas fa-question-circle
title: Warning
content: |
    - For production, use [partner.teya.com](https://partner.teya.com) to generate production credentials.
    - Any portal with ".xyz" is directing to development environment only.
```

### 2. Obtain the Teya Payment App APK and Test Cards

- [Download the Teya mock payment app APK](https://cdn.teya.com/static/2bbd9f0b/TeyaTerminalApp-mock-optimized-v3.11.3-rc01.apk)
- The mock app includes built-in test cards that allow you to simulate various payment scenarios.

### 3. (Optional) Request a Teya Card Machine

- If you prefer, you can use the Teya app on any **Android emulator** for testing.
- Alternatively, you may request a **physical Teya card machine** from your Partnership Manager for real-device testing.

### 4. Start Development

After completing the above steps, you can begin development by integrating the SDK into your Android, iOS or Windows application using the provided guides and code samples.

## Sample Apps

Complete sample applications demonstrating POSLink integration with the Teya Unified ePOS SDK, as reference implementations for learning and development:

```grid
card:
    title-left: Android
    icon: fab fa-android
    link: /epos-sdk/poslink/android/getting-started#sample-app
    content: Connect an Android ePOS application to a separate Teya payment card machine over the cloud.
card:
    title-left: Windows
    icon: fab fa-windows
    link: /epos-sdk/poslink/windows/getting-started#sample-app
    content: Connect a Windows ePOS application to a separate Teya payment card machine over the cloud.
card:
    title-left: iOS
    icon: fab fa-apple
    link: /epos-sdk/poslink/ios/getting-started#sample-app
    content: Connect an iOS ePOS application to a separate Teya payment card machine over the cloud.
```

```admonition
icon: fas fa-code
title: I can't find my SDK
content: Only integrate against the POSLink API directly if no SDK is available for your platform. Where an Android, Windows or iOS SDK covers your platform, always use the SDK.
link: /poslink/develop/authenticate-merchant
```