> ## Documentation Index
> Fetch the complete documentation index at: https://docs.lab4pay.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

## How App2App Fits into Pay-Connect

<Note>
  App2App is an **extension of the Pay-Connect platform**, not a standalone integration. It uses the same infrastructure and credentials as your API integration. It offers fast, low-overhead payment processing for charge, revert, and refund operations.
</Note>

<Columns cols={2}>
  <Card title="Terminal pairing">
    Terminal pairing is always initialized by the backend
  </Card>

  <Card title="Payment processing">
    Payment processing remains consistent with API integrations
  </Card>
</Columns>

<Tabs>
  <Tab title="Use App2App when">
    * You are building an Android POS application
    * You want a fast, low-overhead integration
    * Backend involvement during payment is not required
    * The POS and payment apps run on the same device
  </Tab>

  <Tab title="Use API Integration when">
    * Configuration data
    * Transaction patch (custom metadata)
    * Transaction status polling
    * Webhooks
  </Tab>
</Tabs>

## Supported Operations

<Warning>
  **Supported Operations**\
  App2App supports a **focused set of payment operations** only:

  * **Charge** - Process a payment
  * **Revert** - Cancel a transaction before settlement
  * **Refund** - Return funds after settlement

  All other functionality is available exclusively through API integration.
</Warning>

## App2App flow Overview

<Steps>
  <Step title="Init payment request">
    The POS app initiates a payment request
  </Step>

  <Step title="Transaction process">
    The payment app processes the transaction
  </Step>

  <Step title="Directly returned results">
    The result is returned directly to the POS app
  </Step>
</Steps>

> **Tip:** The exact implementation details are covered in the **Android App2App Integration** guide.

## Next Steps

<Columns cols={2}>
  <Card icon="mobile-notch" title="Android App2App Integration">
    Review the complete implementation guide with code samples and integration steps.
  </Card>

  <Card icon="handshake" title="Terminal Pairing">
    Ensure the terminal is already paired via backend APIs before starting App2App integration.
  </Card>
</Columns>