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

# Kotlin

> Integrate Dodo Payments into your Kotlin applications with modern coroutines and null-safety

The Kotlin SDK provides convenient access to the Dodo Payments REST API from applications written in Kotlin. It features nullable values, Sequence, suspend functions, and other Kotlin-specific features for ergonomic use.

## Installation

### Gradle (Kotlin DSL)

Add the dependency to your `build.gradle.kts`:

```kotlin build.gradle.kts theme={null}
implementation("com.dodopayments.api:dodo-payments-kotlin:1.97.1")
```

### Maven

Add the dependency to your `pom.xml`:

```xml pom.xml theme={null}
<dependency>
  <groupId>com.dodopayments.api</groupId>
  <artifactId>dodo-payments-kotlin</artifactId>
  <version>1.97.1</version>
</dependency>
```

<Tip>
  Always use the latest SDK version to access the newest Dodo Payments features. Check [Maven Central](https://central.sonatype.com/artifact/com.dodopayments.api/dodo-payments-kotlin) for the latest version.
</Tip>

<Info>
  The SDK requires Java 8 or later and is compatible with both JVM and Android platforms.
</Info>

## Quick Start

Initialize the client and create a checkout session:

```kotlin theme={null}
import com.dodopayments.api.client.DodoPaymentsClient
import com.dodopayments.api.client.okhttp.DodoPaymentsOkHttpClient
import com.dodopayments.api.models.checkoutsessions.CheckoutSessionCreateParams
import com.dodopayments.api.models.checkoutsessions.CheckoutSessionRequest
import com.dodopayments.api.models.checkoutsessions.ProductItemReq

// Configure using environment variables (DODO_PAYMENTS_API_KEY, DODO_PAYMENTS_BASE_URL)
// Or system properties (dodopayments.apiKey, dodopayments.baseUrl)
val client: DodoPaymentsClient = DodoPaymentsOkHttpClient.fromEnv()

val params: CheckoutSessionRequest = CheckoutSessionRequest.builder()
    .addProductCart(ProductItemReq.builder()
        .productId("product_id")
        .quantity(1)
        .build())
    .build()
    
val checkoutSessionResponse: CheckoutSessionResponse = client.checkoutSessions().create(params)
println(checkoutSessionResponse.sessionId())
```

<Warning>
  Always store your API keys securely using environment variables or encrypted configuration. Never commit them to version control.
</Warning>

## Core Features

<CardGroup cols={2}>
  <Card title="Coroutines" icon="bolt">
    Full support for Kotlin coroutines for asynchronous operations
  </Card>

  <Card title="Null Safety" icon="shield-check">
    Leverage Kotlin's null safety for robust error handling
  </Card>

  <Card title="Extension Functions" icon="code">
    Idiomatic Kotlin extensions for enhanced functionality
  </Card>

  <Card title="Data Classes" icon="layer-group">
    Type-safe data classes with copy and destructuring support
  </Card>
</CardGroup>

## Configuration

### From Environment Variables

Initialize from environment variables or system properties:

```kotlin theme={null}
val client: DodoPaymentsClient = DodoPaymentsOkHttpClient.fromEnv()
```

### Manual Configuration

Configure manually with all options:

```kotlin theme={null}
import java.time.Duration

val client = DodoPaymentsOkHttpClient.builder()
    .bearerToken("your_api_key_here")
    .baseUrl("https://live.dodopayments.com")
    .maxRetries(3)
    .timeout(Duration.ofSeconds(30))
    .build()
```

### Test Mode

Configure for test/sandbox environment:

```kotlin theme={null}
val testClient = DodoPaymentsOkHttpClient.builder()
    .fromEnv()
    .testMode()
    .build()
```

### Timeouts and Retries

Configure globally or per-request:

```kotlin theme={null}
import com.dodopayments.api.core.RequestOptions

// Global configuration
val client = DodoPaymentsOkHttpClient.builder()
    .fromEnv()
    .timeout(Duration.ofSeconds(45))
    .maxRetries(3)
    .build()

// Per-request timeout override
val product = client.products().retrieve(
    "prod_123",
    RequestOptions.builder()
        .timeout(Duration.ofSeconds(10))
        .build()
)
```

## Common Operations

### Create a Checkout Session

Generate a checkout session:

```kotlin theme={null}
val params = CheckoutSessionRequest.builder()
    .addProductCart(ProductItemReq.builder()
        .productId("prod_123")
        .quantity(1)
        .build())
    .returnUrl("https://yourdomain.com/return")
    .build()

val session = client.checkoutSessions().create(params)
println("Checkout URL: ${session.checkoutUrl()}")
```

### Create a Product

Create products with detailed configuration:

```kotlin theme={null}
import com.dodopayments.api.models.products.Product
import com.dodopayments.api.models.products.ProductCreateParams
import com.dodopayments.api.models.misc.Currency
import com.dodopayments.api.models.misc.TaxCategory

val createParams = ProductCreateParams.builder()
    .name("Premium Subscription")
    .description("Monthly subscription with all features")
    .price(
        ProductCreateParams.RecurringPrice.builder()
            .currency(Currency.USD)
            .preTaxAmount(2999) // $29.99 in cents
            .paymentFrequencyInterval(ProductCreateParams.RecurringPrice.TimeInterval.MONTH)
            .paymentFrequencyCount(1)
            .build()
    )
    .taxCategory(TaxCategory.DIGITAL_GOODS)
    .build()

val product: Product = client.products().create(createParams)
println("Created product ID: ${product.productId()}")
```

### Activate License Key

Activate license keys for customers:

```kotlin theme={null}
import com.dodopayments.api.models.licenses.LicenseActivateParams
import com.dodopayments.api.models.licenses.LicenseActivateResponse

val activateParams = LicenseActivateParams.builder()
    .licenseKey("XXXX-XXXX-XXXX-XXXX")
    .instanceName("user-laptop-01")
    .build()

try {
    val activationResult: LicenseActivateResponse = client.licenses()
        .activate(activateParams)

    println("License activated successfully")
    println("Instance ID: ${activationResult.instanceId()}")
    println("Expires at: ${activationResult.expiresAt()}")
} catch (e: UnprocessableEntityException) {
    println("License activation failed: ${e.message}")
}
```

### Handle Subscriptions

Create and manage recurring subscriptions:

```kotlin theme={null}
import com.dodopayments.api.models.payments.AttachExistingCustomer
import com.dodopayments.api.models.payments.BillingAddress
import com.dodopayments.api.models.payments.CountryCode
import com.dodopayments.api.models.subscriptions.SubscriptionChargeParams
import com.dodopayments.api.models.subscriptions.SubscriptionCreateParams

// Create a subscription
val subscriptionParams = SubscriptionCreateParams.builder()
    .billing(BillingAddress.builder()
        .city("San Francisco")
        .country(CountryCode.US)
        .state("CA")
        .street("1 Market St")
        .zipcode("94105")
        .build())
    .customer(AttachExistingCustomer.builder()
        .customerId("cus_123")
        .build())
    .productId("pdt_456")
    .quantity(1)
    .build()

val subscription = client.subscriptions().create(subscriptionParams)
println("Subscription ID: ${subscription.subscriptionId()}")

// Charge an on-demand subscription
// productPrice is in the lowest currency denomination (e.g., 2500 = $25.00 USD)
val chargeParams = SubscriptionChargeParams.builder()
    .subscriptionId(subscription.subscriptionId())
    .productPrice(2500)
    .build()

val chargeResponse = client.subscriptions().charge(chargeParams)
println("Payment ID: ${chargeResponse.paymentId()}")
```

<Info>
  `billing` requires at minimum a two-letter ISO `country` code. Use `AttachExistingCustomer` to attach an existing customer, or `NewCustomer` to create one. `productPrice` is expressed in the lowest currency denomination.
</Info>

## Usage-Based Billing

### Record Usage Events

Track usage for meters:

```kotlin theme={null}
import com.dodopayments.api.models.usageevents.UsageEventCreateParams
import java.time.OffsetDateTime

val usageParams = UsageEventCreateParams.builder()
    .meterId("meter_123")
    .customerId("cust_456")
    .value(150)
    .timestamp(OffsetDateTime.now())
    .build()

client.usageEvents().create(usageParams)
println("Usage event recorded")
```

## Async Operations

### Async Client

Use the async client for coroutine-based operations:

```kotlin theme={null}
import com.dodopayments.api.client.DodoPaymentsClientAsync
import com.dodopayments.api.client.okhttp.DodoPaymentsOkHttpClientAsync
import kotlinx.coroutines.runBlocking

val asyncClient: DodoPaymentsClientAsync = DodoPaymentsOkHttpClientAsync.fromEnv()

runBlocking {
    val customer = asyncClient.customers().retrieve("cust_123")
    println("Customer email: ${customer.email()}")
}
```

## Error Handling

Handle errors with Kotlin's exception handling:

```kotlin theme={null}
import com.dodopayments.api.errors.*

try {
    val payment = client.payments().create(params)
    println("Success: ${payment.id()}")
} catch (e: AuthenticationException) {
    println("Authentication failed: ${e.message}")
} catch (e: InvalidRequestException) {
    println("Invalid request: ${e.message}")
    e.parameter?.let { println("Parameter: $it") }
} catch (e: RateLimitException) {
    println("Rate limit exceeded, retry after: ${e.retryAfter}")
} catch (e: DodoPaymentsServiceException) {
    println("API error: ${e.statusCode()} - ${e.message}")
}
```

### Functional Error Handling

Use `Result` for functional error handling:

```kotlin theme={null}
fun safeCreatePayment(client: DodoPaymentsClient): Result<Payment> = runCatching {
    client.payments().create(params)
}

// Usage
safeCreatePayment(client)
    .onSuccess { payment -> println("Created: ${payment.id()}") }
    .onFailure { error -> println("Error: ${error.message}") }
```

<Tip>
  Use Kotlin's `runCatching` for a more functional approach to error handling with Result types.
</Tip>

## Android Integration

Use with Android applications:

```kotlin theme={null}
import android.app.Application
import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import com.dodopayments.api.client.DodoPaymentsClient
import kotlinx.coroutines.launch

class PaymentViewModel(application: Application) : ViewModel() {
    private val client = DodoPaymentsOkHttpClient.builder()
        .bearerToken(BuildConfig.DODO_API_KEY)
        .build()
    
    fun createCheckout(productId: String) {
        viewModelScope.launch {
            try {
                val session = client.async().checkoutSessions().create(params)
                // Open checkout URL in browser or WebView
                openUrl(session.checkoutUrl())
            } catch (e: Exception) {
                handleError(e)
            }
        }
    }
}
```

## Response Validation

Enable response validation:

```kotlin theme={null}
import com.dodopayments.api.core.RequestOptions

// Per-request validation
val product = client.products().retrieve(
    "prod_123",
    RequestOptions.builder()
        .responseValidation(true)
        .build()
)

// Or validate explicitly
val validatedProduct = product.validate()
```

## Advanced Features

### Proxy Configuration

Configure proxy settings:

```kotlin theme={null}
import java.net.InetSocketAddress
import java.net.Proxy

val client = DodoPaymentsOkHttpClient.builder()
    .fromEnv()
    .proxy(
        Proxy(
            Proxy.Type.HTTP,
            InetSocketAddress("proxy.example.com", 8080)
        )
    )
    .build()
```

### Temporary Configuration

Modify client configuration temporarily:

```kotlin theme={null}
val customClient = client.withOptions {
    it.baseUrl("https://example.com")
    it.maxRetries(5)
}
```

## Ktor Integration

Integrate with Ktor server applications:

```kotlin theme={null}
import io.ktor.server.application.*
import io.ktor.server.request.*
import io.ktor.server.response.*
import io.ktor.server.routing.*

fun Application.configureRouting() {
    val client = DodoPaymentsOkHttpClient.builder()
        .bearerToken(environment.config.property("dodo.apiKey").getString())
        .build()
    
    routing {
        post("/create-checkout") {
            try {
                val request = call.receive<CheckoutRequest>()
                val session = client.checkoutSessions().create(params)
                call.respond(mapOf("checkout_url" to session.checkoutUrl()))
            } catch (e: DodoPaymentsServiceException) {
                call.respond(HttpStatusCode.BadRequest, mapOf("error" to e.message))
            }
        }
    }
}
```

## Resources

<CardGroup cols={2}>
  <Card title="GitHub Repository" icon="github" href="https://github.com/dodopayments/dodopayments-kotlin">
    View source code and contribute
  </Card>

  <Card title="API Reference" icon="book" href="/api-reference/introduction">
    Complete API documentation
  </Card>

  <Card title="Discord Community" icon="discord" href="https://discord.gg/bYqAp4ayYh">
    Get help and connect with developers
  </Card>

  <Card title="Report Issues" icon="bug" href="https://github.com/dodopayments/dodopayments-kotlin/issues">
    Report bugs or request features
  </Card>
</CardGroup>

## Support

Need help with the Kotlin SDK?

* **Discord**: Join our [community server](https://discord.gg/bYqAp4ayYh) for real-time support
* **Email**: Contact us at [support@dodopayments.com](mailto:support@dodopayments.com)
* **GitHub**: Open an issue on the [repository](https://github.com/dodopayments/dodopayments-kotlin)

## Contributing

We welcome contributions! Check the [contributing guidelines](https://github.com/dodopayments/dodopayments-kotlin/blob/main/CONTRIBUTING.md) to get started.