← Back to Blog

In-depth Recap of the xCall Incentivized Testnet Program

Testnet Recap

October 30, 2023



Full Story

Earlier this year we ran the first phase of our xCall Incentivized Testnet Program, our goal was to target both high-value submissions that could contribute something important to the early stages of the xCall ecosystem and projects that have potential for further development. 

As you may have read in the brief recap, we had 18 submissions that were eligible for about 330,000 ICX in rewards. These developments ranged from Twitter spaces to message trackers to dApp demos. It was very exciting to see so much innovation and enthusiasm in such a short time, especially for a new and previously unexplored product.

Let’s take a deep dive into the results from Phase 1 of the Incentivized xCall Testnet Program. 

Tools Divider

As a technology service layer, the most important outcome of the Incentivized xCall Testnet Program was in-depth product demonstration by technology development groups. Through these developments, we can see how xCall works and how it can be used to build services on top of.

xCall Chainlink VRF

This project by Paul Rouge demonstrates how random numbers can be read on-chain from a chain without a Verifiable Randomness Function generator. Basically, another closed-network blockchain has a random number generator that can be used by dApps. That random number generator is attached to the xCall service, and upon request, the random number is sent to another xCall-integrated chain. In the example provided, Paul supplies random numbers from Ethereum to ICON. Random numbers can be used by dApps to provide seeds that can be turned into unpredictable results, for example selecting a random entry from a set.


This is the second winning project by Paul Rouge on behalf of a development organization called Onyxgrid that he is looking to further establish. One of the biggest challenges with a cross-chain system is that executing transactions is actually a multi-step process. First, the transaction must be submitted on one chain. Then, it makes its way to the second chain, where xCall assists to verify that the transaction is actually intended to be executed. Then, the caller can actually execute the transaction on the second chain. It is setup this way because dApp developers may only want certain parties to be able to submit transactions on behalf of a specific account. This is a change from the previous system, where submitting a transaction can be done in a single step.

However, this presents a new challenge to developers, where they don’t necessarily want to pay attention to another chain to notify them when the next transaction is ready to be executed. To solve this, Paul developed xCalligraph, which allows developers to register multiple accounts as belonging to a single development party. It is essentially an automated signing service. Developers may be able to save a lot of time by using a ready-made, automated tool instead of creating a custom solution.

Galactic Conquest + XChainMultitoken

Galactic Conquest is an expansion of the Inanis Invictus game, which has been in development in the ICON ecosystem for a little while now. For the testnet program, lead developer Brandon has created two things that are important for the xCall ecosystem. One, he has demonstrated how to use xCall between HAVAH chain and ICON chain. HAVAH being one of the partner projects that also uses the goloop blockchain engine, and is also working with the Parameta team as a technical partner. The second technical feat is the creation of the XChain Multitoken standard, which is a way to track and transfer token assets between xCall-integrated blockchains. It aims to have a high degree of compatibility with the IRC-2 / ERC-20 token standards. This standard is in the review phase to be added as an ICON Improvement Proposal. Developers can use this standard to create their own cross-chain token.


A Developer under the moniker ‘kryptopoo’ has created a tracker for xCall, called ‘xCallScan’. It is actively tracking testnet transactions between ICON Berlin, HAVAH Altair, Ethereum Sepolia, and Binance Smart Chain Testnet. The tracker is very elegant looking, and it is very simple to see the path and state of transactions between xCall-connected chains.

Omni Name Service

The Omni Name Service is an exciting project for the xCall ecosystem. Similarly to the xCalligraph project, this project aims to solve the issue of combining identities between the closed blockchain networks. Basically, users can register a unified identity that connects with  This helps developers and users trigger actions on their behalf with different Externally Owned Accounts native to each closed chain. This app currently works between ICON Berlin and Binance Smart Chain Testnet. It is another app that would be a big value-add to the xCall ecosystem if brought to production.

xCall Tracker

This is the second xCall tracker, which is by the Techiast team. This one works a bit differently. Basically, it is a service that can track a specific set of contracts that are integrated with xCall. It is also integrated into their 1ClickNode service, which is currently in demo mode. This addition to the service adds a new type of ‘node’, called an xCall API node. You can automatically deploy this node and use it to check what’s happening with your application.


Another addition to the infrastructure layer of xCall here is Aurras, developed by HugoByte. Aurras is a project for pushing arbitrary notifications to any user that runs or subscribes to the service. In this case, they have developed a modification to the Aurras system that tracks xCall-related events on ICON and EVM chains. This is useful for developers to coordinate between their different cross-chain components. Think of it somewhat like the Ethereum Push Notification Service.

HugoByte also develops the DIVE tool, which is used to setup local cross-chain testing environments.


The xCallympics project is by the Staky team that produces Craft Network. It is a demonstration of how NFTs can be minted and transferred across multiple chains. This project shows this behavior between ICON and EVM chains. NFTs are useful for unique asset tracking, and so this is a good example of how to extend that so that tracking is synchronized between closed blockchain networks.

Users Divider

We also saw some high quality community content and bug reports come in. These efforts increase communication both external and internal to the community, so that we can let other developers know about xCall and so that our team can improve the product based on issues that come up.

withICONists xCall Twitter Space

The withICONists DAO hosted one of their monthly Twitter Spaces with a direct focus on marketing and promotion efforts for xCall. This space was hosted by Encrypto and Budw1ser, two leading members of the DAO. This is a great example of community members taking ownership of the decentralized ICON product ecosystem. This DAO is led by longstanding ICON Community Managers John and Arosh, based in the ICON Community Discord. It is important for community members to have a stake in the decentralized ecosystem so that they can benefit from its sustained growth based on their own skills and motivations. This Twitter Space and the withICONists DAO in general is a great example of using an existing community to market themselves for providing a useful and trustworthy service.

Twitter Space link: https://twitter.com/helloiconworld/status/1684230712516550657?s=20

xRum multi-blockchain user preference system design

For those who wish to gain insight into possible future development paths for cross-chain technology, we highly recommend reading this article by Jimmy Debe. This article describes in-depth how a user preference system can be constructed based on xCall, considering the inherent technical problems with development between closed blockchain networks. In essence, a preference system can be constructed to provide a token containing information about user preference details and appropriate proofs. This system falls within the scope of Decentralized Identity and can be used to augment an account system.

Article link: https://medium.com/@jimstir/xrum-a-multi-blockchain-user-preference-interface-b3347db3a409

Bug Reports

Next Steps

Get ready for the next exciting chapter of our journey with Phase 2 of the Incentivized xCall Testnet! In this upcoming phase, we're thrilled to be collaborating with innovative organizations who are keen to explore the potential of xCall. But that's not all - we're also on the hunt for brilliant developers, creative minds, and passionate community members who are ready to help us craft a product ecosystem that truly revolutionizes the world of cross-chain messaging and trust-based application development. Stay tuned for more details in the days ahead!