As the Ethereum blockchain matures, more test networks have emerged to help core developers and Ethereum dApp developers prepare for Ethereum’s upcoming merge to proof of stake. 

Two of the testnets, Kintsugi and Kiln, focus on preparing for the upcoming launch of Ethereum’s new consensus layer upgrade. 

This article will compare the  Kiln and Kintsugi testnets and show how to use them.

The biggest similarity between Kiln and Kintsugi is their consensus mechanism: proof-of-stake (PoS) instead of proof-of-work (PoW). Having undergone the long-anticipated Merge, both Kiln and Kintsugi use the eco-friendly consensus layer with cheaper gas. The client developer intends this transition from PoW to PoS to uncover any major issues before the completion of the Merge later this year.   

The Kintsugi test blockchain was launched by the Ethereum Foundation as an Ethereum community initiative in December 2021. Kintsugi was the first “longer-lived public testnet” intended for initial merge testing. Similarly, the Kiln testnet was launched by Ethereum in March 2022 as the second testnet to experiment with the post-merge environment.

Both merge testnets are shadow forks of the Ethereum chain. Thus, they are identical to the Ethereum chains and thus are completely EVM-compatible.

As the testnets simulate post-merge environments, they use Beacon nodes and Execution engines in their consensus clients, handled by the existing execution layer client (pre-merge). 

While both layers maintain independent API endpoints, they are intertwined with peer-to-peer connections to bridge the Eth1 clients with the PoS mechanism of Beacon chains. 

More information about Ethereum’s post-merge architecture can be found in Tim Beiko’s AllCoreDevs update 007 on Mirror.

The main difference between the Kiln and Kintsugi testnets is one is still active and the other is deprecated. In its early months, the Kintsugi testnet experienced major client bugs that resulted in the network forking twice. Soon after, the Kiln testing network was launched with improvements to re-test the post-merge environment. After the launch of the Kiln testnet, the Kintsugi network was officially deprecated.

Since the Kintsugi testnet is officially deprecated after the unexpected forks, we recommend developers use the Kiln testnet and get Kiln ETH tokens from a Kiln faucet.

The Kiln testnet provides the community (e.g. node operators, developers, stakers, etc.) with an opportunity to experiment on a post-merge Ethereum blockchain. Developers are highly encouraged to test out applications on the Kiln testnet and report issues or feedback to help the core Ethereum developers complete a smooth transition to proof-of-stake.

However, with the Ropsten testnet merge to proof-of-stake, Tim Beiko, stated that the Kiln testnet will be shut down soon after merge. After the mainnet merge, the only two testnets that will be maintained are Goerli and Sepolia.

To start testing applications on Goerli, get Goerli ETH tokens from Alchemy’s Goerli faucet.