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

# Overview

The **TransactBridge Android Drop-in SDK** lets you add a complete, secure payment experience to your app with minimal code. It supports card and UPI payments, handles UI, validation, and security, and provides a smooth user experience.

## Integration Methods

You can integrate the SDK in three ways:

* **Direct AAR file:** Build or download the AAR and add it to your app's `libs/` directory.
* **Maven Local:** Publish the SDK to your local Maven repository and add it as a dependency.
* **Maven Central:** (Coming soon) Add the SDK as a dependency from Maven Central.

See [Quick Start](/checkout.js/android-sdk/dropin/quickstart) for step-by-step instructions for each method.

## What does the Drop-in SDK provide?

The Drop-in SDK offers:

* Pre-built payment sheet (UPI, Terms & Conditions)
* PCI-compliant, secure payment handling
* UPI app listing and deep linking
* Customizable theming
* Device and network security checks
* Simple callback-based integration

## How the Drop-in SDK Works

1. Add the SDK to your project (AAR or Maven)
2. Initialize the SDK with your publishable key and endpoints
3. Add the Terms & Conditions view to your layout
4. Launch the payment sheet with a config object
5. Handle payment results via callback

## Key Concepts

* **PaymentSDK**: Entry point for all payment operations. Handles initialization and launching the payment sheet.
* **PaymentConfig**: Holds all parameters for a payment (session, token, T\&C, etc.).
* **PaymentResultCallback**: Interface for handling payment results (success, failure, cancel).
* **TermsAndConditionsView**: UI component for user consent.
* **UPI App Listing**: Utility to list and launch UPI apps for payment.