The Ethereum ecosystem is constantly changing and improving, including the testnets landscape. These testnets play a critical role in shaping the future of the network. Therefore, developers and stakeholders within the Ethereum ecosystem must understand these testnets’ intricacies to deploy projects successfully. 

The introduction of Holesky is a significant milestone in Ethereum’s ongoing evolution, particularly with its ambitious goal of supporting a wide range of validators. This article will provide details about Sepolia and Holesky, highlighting their unique features, purposes, and how they cater to different needs within the Ethereum ecosystem.

What Is Sepolia?

Sepolia was launched in October 2021 with a proof-of-work mechanism but was later transitioned to a proof-of-stake mechanism as a test for executing The Merge on testnet in preparation for executing it on Ethereum mainnet. Sepolia is primarily designed as a developer’s playground, providing a precise testing environment for smart contracts and decentralized applications (dApps). The platform boasts fast syncing and a permissioned set of validators, making it an efficient option for developers focused on dApp development. Additionally, Sepolia has unlimited sepETH (Sepolia ETH), which eliminates the bottlenecks experienced on Goerli.

What Is Holesky?

Holesky was launched in September 2023 as the latest Ethereum testnet, replacing Goerli. It serves as a network for testing validation and staking and is open for users who want to test protocol upgrades before deploying them on mainnet. Holesky aims to address the scalability issues that Goerli faced, such as the shortage of goETH (Goerli ETH) and high demand. Holesky has approximately 1.6 billion holETH (Holesky ETH) available, which should resolve the goETH shortage issue. Moreover, Holesky enables more robust testing for validators, with over 1.5 million validators active on the network—more than Ethereum mainnet and Goerli combined. This large set of validators creates an environment that allows for detecting any scaling issues that may arise.

Sepolia vs. Holesky: Key Differences

It is important to note that the designs of Sepolia and Holesky serve different purposes. Below are the key differences between them.

Validator Sets

Sepolia: Sepolia has a closed validator set, making it easy to sync, and requiring minimal disk space to run a node.

Holesky: Holesky is open to new validators, with over 1.5 million validators running on the testnet.

Test Token Supply Mechanics

Sepolia: Sepolia has an uncapped token supply.

Holesky: While not unlimited, Holesky’s has a capped supply of holETH at 1.6 billion, more than twice the amount issued on Goerli.

Intended Use Case

Sepolia: Sepolia is the best place to test smart contracts and dApps.

Holesky: The intent of Holesky is testing validators and staking. 

Sepolia and Goerli Testnet Faucets

Using the Chainlink Testnet Faucet, you can request testnet tokens to test your Chainlinked smart contract on a variety of testnets. Go to https://faucets.chain.link/sepolia to request testnet tokens on Sepolia, or go to https://faucets.chain.link/goerli to request testnet tokens on Goerli.