ChainSafe supports Ephemery: Ethereum’s ever-refreshing testnet
This lightweight, resetting testnet gives you a clean slate every four weeks. It's perfect for testing staking setups, validator configurations, and smart contract deployments.
Ephemery isn’t your typical testnet—Ephemery is making it easier than ever to fine-tune staking infrastructure before entering the mainnet.
Ephemery is designed to reset to genesis every 28 days, allowing for rapid and no-risk experimentation for Ethereum developers and staking infrastructure teams. Ephemery is a fresh playground for testing integrations, validator setups, and client performance without the baggage of long-term state bloat.
With Ethereum’s Pectra fork just around the corner, developers and staking infrastructure teams can look to Ephemery as a quick and clean test environment for the incoming upgrades.
What is Ephemery?
Originally proposed by Mario Havel (GitHub, X) of the Ethereum Foundation's Protocol Support team, Ephemery is a community-driven testnet that aims to give developers a cross-client testnet free from the issues stemming from a long-running network history.
As a testnet runs for a long period and gets old, it becomes less practical for actual testing. It grows in size making it harder to sync, the validator set can become unstable, and—more importantly—the actual testnet ETH coins are running out. — Mario Havel
Ephemery is a new kind of Ethereum testnet that’s designed to reset automatically at regular intervals. By ensuring that each iteration starts from a fresh genesis state, Ephemery provides a bloat-free environment for developers and stakers to conduct iterative, short-term testing.
The idea came up at Devcon in Bogota, during a time that these issues with testnets were at their worst. As the community realized that even long-term testnets need to have a clear deprecation schedule, we thought of creating a single testnet which would reset periodically. — Mario Havel
Key features of Ephemery
- Lightweight and efficient: Because Ephemery resets regularly, it doesn’t pile up historical data like other testnets. This keeps it lean and fast, making it much easier to spin up and start testing without unnecessary bloat.
- Quick sync times: No more waiting for your node to catch up! Ephemery’s smaller state size syncs in minutes, allowing developers and validators to jump into testing without the usual delays.
- Perfect for rapid testing: Ephemery wipes the slate clean with every reset, making it the ideal playground for experimenting with applications, validator setups, and client implementations.
- Undrainable faucets: Every time Ephemery resets, testnet ETH funds are returned to their faucets for a fresh new cycle.
Read the original Ephemery proposal here:
Comparison to other Ethereum testnets
Traditional Ethereum testnets like Goerli and Sepolia are designed for long-term stability, maintaining persistent states that grow over time. While this persistence is beneficial for certain types of testing, it can lead to challenges such as state bloat, longer synchronization times, the need for substantial storage resources.
In contrast, Ephemery's scheduled resets ensure that the network remains efficient and easy to manage. This approach offers a unique advantage for developers and stakers seeking a streamlined environment for rapid iteration and testing.
Who’s using Ephemery?
Like many great ideas, the ensuing use-cases tend to exceed the original goals. We asked Mario Havel what kind of use Ephemery was seeing already as Ethereum’s first regenerating testnet:
"Our original expectation was that stakers will use this testnet the most. There weren't any permissionless faucets giving out 32+ ETH on Sepolia so we wanted to provide an environment where it's easy to try it out as a home staker or even larger staking operation.
However, after Remix started supporting Ephemery, it turned out to be a popular place for people learning dapp development. Developers can easily deploy and test their contracts without bloating the state. Every 'hello world' that would stay on other chains forever will be gone from Ephemery in less than a month.
Surprisingly, the minimal size of the chain prompted another interesting use-case: we found out that National University of Asuncion (Paraguay) uses Ephemery, where students use the network to run their own nodes while studying blockchain development. Everyone can easily spin up their own client to do experiments, making it a great tool for education." — Mario Havel
ChainSafe’s role: genesis validators
ChainSafe began developing genesis validators for Ephemery in December 2024 and, today, runs 4000 validator keys that support each network reset.
A diverse set of community validators helps the Ephemery community “sleep much more calmly”, as Mario puts it, since the responsibility of the testnet’s most critical feature is becomes more effectively decentralized.
Initially we started this as three people running nodes. That's not decentralized or sustainable. Even though there are more validators now, they are all active members of the community who contribute a lot, like quickly coordinating to test new forks, for example.
Every 28 days, the Ephemery testnet reiterates from a new genesis that is deterministically created based on the previous one. The main changes in the genesis are chainId, timestamp, and the withdrawal credentials of the first validator.
At the very beginning of the testnet, in period 0 (zero), the network starts with genesis 0 (zero), which is hardcoded in the client. However, during each client start, the client builds a new genesis based on genesis 0. This new genesis is written to the database and used to run the current network.
Genesis validators are integral to the launch and stability of a blockchain network, ensuring the chain’s initial blocks are confirmed. Typically, genesis validators fill a one-time role in a blockchain’s launch before disappearing or switching to regular validator status.
In Ephemery, however, genesis occurs in regular intervals. ChainSafe’s 4000 genesis validators for the Ephemery testnet help to run this usually unique occurrence once every 28 days, ensuring the network's stability and reliability during each reset.
Preparing for Pectra with Ephemery
Ethereum’s upcoming Pectra hard fork is a significant step forward, bringing improvements to scalability, user experience, and staking efficiency. Planned initially as Ethereum’s most ambitious upgrade ever—packing in up to 20 Ethereum Improvement Proposals (EIPs)—Pectra has now been split into two phases to keep things smooth and manageable.
With these changes on the horizon, developers and validators need reliable ways to test their integrations before the fork goes live. We asked proposal-originator Mario Havel who might get benefit the most from Ephemery leading up to Pectra:
- Core developers get a unique opportunity in Ephemery to further debug their clients, and eager users can test-drive the new features introduced in Pectra.
- App developers can be first to try new account abstractions enabled with EIP-7702, testing early to make sure their contracts work well under the new fork.
- Stakers might appreciate Ephemery the most, as Pectra introduces new max effective balance and enables validator aggregation up to 2048 ETH. The only other public testnet with an open validator set is Sepolia, where it’s hard to obtain large amounts of ETH. Stakers on Ephemery, on the other hand, can spin up as many validators as they wish.
.@ephemerytestnet is awesome. Probably the best place for anyone to test how Pectra 0x02 credential changes could affet max effective balance on their validators. Ephemery resets every thirty days and is about to include Pectra! Join us! pic.twitter.com/hPkwzAQSJq
— superphiz.eth 🦇🔊🛡️ (@superphiz) February 9, 2025
Pectra introduces game-changing updates to Ethereum’s staking and execution layers, but testing these changes in a long-running testnet can be slow and cumbersome.
With Pectra expected to roll out in early 2025, developers and validators should prepare now. By leveraging Ephemery’s lightweight, fast-syncing environment, they can experiment freely and ensure a smooth transition when the fork arrives.
Smarter accounts (EIP-7702): rapid testing in Ephemery
With Pectra’s introduction of one-click smart accounts, developers will need to test how these accounts interact with dApps, wallets, and other smart contract systems. Since Ephemery wipes the slate clean every few weeks, it’s a perfect place to experiment without worrying about legacy data or long sync times.
Bigger staking limits (EIP-7251): validator testing in Ephemery
The increase in Ethereum’s staking limit means infrastructure providers and solo stakers need to adjust their setups. Running validators on Ephemery lets teams quickly test new configurations, ensuring they’re ready for Pectra without having to deal with an overgrown testnet.
More data, faster scaling: stress testing in Ephemery
Pectra temporarily increases Ethereum’s data availability capacity, but future upgrades like PeerDAS will demand even more testing. Since Ephemery resets frequently, it offers a clean testing ground for data-heavy applications, helping devs refine their solutions before deploying to a more permanent testnet or mainnet.
Get involved in Ephemery
If you're an Ethereum developer, educator, validator, or staking provider, now is the time to start using Ephemery.
This lightweight, resetting testnet gives you a clean slate every four weeks. It’s the perfect place to test new staking setups, validator configurations, and smart contract deployments—without the baggage of long-running testnets.
Whether you're experimenting with Pectra’s smart accounts, optimizing staking strategies, or stress-testing dapps, Ephemery provides a low-risk, high-speed environment to refine your work before pushing it to mainnet.
Get involved, test your integrations, and be part of Ethereum’s journey!
ChainSafe thanks Mario Havel for his contributions to this article.
About ChainSafe
ChainSafe is a leading blockchain research and development firm specializing in protocol engineering, cross-chain interoperability, and web3-enabled gaming.
Alongside its contributions to major ecosystems such as Ethereum, Polkadot, Filecoin, ChainSafe creates solutions for developers and teams across web3.
As part of its mission to build innovative products for users and improved tooling for developers, ChainSafe embodies an open source and community-oriented ethos to advance the future of the internet.
