Kotlin Client Library

Last updated 18 days ago

The developers guide to building on the Radix Test Network with the Kotlin Client Library

The Kotlin Client library for interacting with a Radix Distributed Ledger compatible with Kotlin/Java projects and maximizing compatibility with all versions of Android.

Compatibility with lower versions of Android is achieved by avoiding the use of any Java 8 APIs e.g. Stream, Optional, Function, etc and using Kotlin built in alternatives.

Code style

This project uses ktlint via Gradle dependency. To check code style - gradle ktlint (it's also bound to gradle check).


  • Connection to the Alphanet test network

  • Fee-less transactions for testnets

  • Identity Creation

  • Native token transfers

  • Immutable data storage

  • Instant Messaging and TEST token wallet Dapp implementation

  • RXJava 2 based

  • Utilizes JSON-RPC over Websockets


Include the following Gradle dependency

repositories { maven { url 'https://jitpack.io' }}​
dependencies { implementation 'com.radixdlt:radixdlt-kotlin:0.11.3'}


An Identity is the user's credentials (or more technically the manager of the public/private key pair) into the ledger, allowing a user to own tokens and send tokens as well as decrypt data.

To create/load an identity from a file:

val identity: RadixIdentity = RadixIdentities.loadOrCreateEncryptedFile("filename.key", "password")

This will create a new file which stores the public/private key and encrypted with the given password.


A Universe is an instance of a Radix Distributed Ledger which is defined by a genesis atom and a dynamic set of unpermissioned nodes forming a network.

To bootstrap to the Alphanet test network:


NOTE: No network connections will be made yet until it is required.

Radix Dapp API

The Radix Application API is a client side API exposing high level abstractions to make DAPP creation easier.

To initialize the API:

RadixUniverse.bootstrap(Bootstrap.ALPHANET) // This must be called before RadixApplicationAPI.create()val api: RadixApplicationAPI = RadixApplicationAPI.create(identity)


An address is a reference to an account and allows a user to receive tokens and/or data from other users.

You can get your own address by:

val myAddress: RadixAddress = api.myAddress

Or from a base58 string:

val anotherAddress: RadixAddress = RadixAddress.fromString("JHB89drvftPj6zVCNjnaijURk8D8AMFw4mVja19aoBGmRXWchnJ")

Storing and Retrieving Data

Immutable data can be stored on the ledger. The data can be encrypted so that only selected identities can read the data.

To store the encrypted string Hello which only the user can read:

val myPublicKey: ECPublicKey = api.myPublicKeyval data: Data = Data.DataBuilder() .bytes("Hello".toByteArray()) .addReader(myPublicKey) .build()result: Result = api.storeData(data, <address>)

To store unencrypted data:

val data: Data = Data.DataBuilder() .bytes("Hello World".toByteArray()) .unencrypted() .build()val result: Result = api.storeData(data, <address>)

The returned Result object exposes RXJava interfaces from which you can get notified of the status of the storage action:

result.toCompletable().subscribe(<on-success>, <on-error>)

To then read (and decrypt if necessary) all the readable data at an address:

val readable: Observable<UnencryptedData> = api.getReadableData(<address>)readable.subscribe { data -> ... }

NOTE: data which is not decryptable by the user's key is simply ignored

Sending and Retrieving Tokens

To send an amount of TEST (the testnet native token) from my account to another address:

val result: Result = api.sendTokens(<to-address>, Amount.of(10, Asset.TEST))

To retrieve all of the token transfers which have occurred in my account:

val transfers: Observable<TokenTransfer> = api.getMyTokenTransfers(Asset.TEST)transfers.subscribe { tx -> ... }

To get a stream of the balance of TEST tokens in my account:

val balance: Observable<Amount> = api.getMyBalance(Asset.TEST)balance.subscribe { bal -> ... }

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