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

# Kotlin SDK Quickstart

> Install the Android Kotlin OMS Wallet SDK, create a client, and authenticate a wallet.

The Kotlin SDK is an Android library. It requires Android `minSdk 26`, Android `compileSdk 34` or newer, Java 17 Android compile options, Kotlin, a project access key, and a project ID.

## Install

Add the SDK dependency from Maven Central to your app module.

```kotlin theme={null}
dependencies {
    implementation("io.github.0xsequence:oms-client-kotlin-sdk:0.1.0-alpha.1")
}
```

This is the only artifact consumers need. The generated wallet API client is packaged inside the AAR as an internal implementation detail.

## Create The Client

Use the Android constructor to get secure session persistence and a non-extractable Android Keystore P-256 request credential.

```kotlin theme={null}
import com.omsclient.kotlin_sdk.OMSClient

val client = OMSClient(
    context = context,
    publishableKey = "YOUR_PROJECT_ACCESS_KEY",
    projectId = "YOUR_PROJECT_ID",
)
```

Create the client once for the app session.

The client exposes:

| Property                   | Use                                                                                             |
| -------------------------- | ----------------------------------------------------------------------------------------------- |
| `client.wallet`            | Authentication, wallet selection, signing, signature verification, ID tokens, and transactions. |
| `client.indexer`           | Token balance reads.                                                                            |
| `client.session`           | Completed wallet-session state restored from Android-backed storage.                            |
| `client.supportedNetworks` | Networks supported by this SDK build.                                                           |

## Authenticate With Email

Email auth is a two-step OTP flow. Call these methods from a coroutine.

```kotlin theme={null}
import com.omsclient.kotlin_sdk.wallet.CompleteAuthResult

if (client.wallet.walletAddress == null) {
    client.wallet.startEmailAuth("user@example.com")

    // Show your OTP input, then complete auth with the user-entered code.
    val result = client.wallet.completeEmailAuth("123456")
    check(result is CompleteAuthResult.WalletSelected)

    println("Wallet address: ${result.walletAddress}")
}
```

`completeEmailAuth` resolves the authenticated wallet. If one matching wallet exists, it uses it. If none exists, it creates one.

## Send A Transaction

After authentication, send a native token transaction with `client.wallet.sendTransaction`. Values are raw base-unit integers.

On testnets, fee options are automatically sponsored, so Polygon Amoy is a good first network for testing.

```kotlin theme={null}
import com.omsclient.kotlin_sdk.Network
import java.math.BigInteger

val tx = client.wallet.sendTransaction(
    network = Network.AMOY,
    to = "0xRecipient",
    value = BigInteger.ZERO,
)

println("Transaction id: ${tx.txnId}")
println("Transaction hash: ${tx.txnHash}")
```