While these three testnets are now considered deprecated, users and developers still have time to plan their migration before they are completely shut down. Below is the timeline for when these three will be shut down.
Kiln: After Mainnet Merge
The Kiln testnet, launched in 2022 to provide a post-merge testing environment, will be shut down shortly after the Ethereum mainnet’s transition to proof-of-stake, expected in the second half of 2022.
Developers should not use Kiln as a long-lasting testing environment. It is expected to be the first testnet to be shut down after The Merge happens on the Ethereum mainnet.
Ropsten: Q4 2022
The Ropsten testnet, which ran through The Merge on June 8, 2022, will be shut down in Q4 2022.
Developers who currently use Ropsten as a staging/testing environment should migrate to Goerli or Sepolia.
Rinkeby: Q2/Q3 2023
The Rinkeby testnet will not run through The Merge. It is being replaced by Sepolia, and will be shut down roughly one year after Sepolia has transitioned to proof-of-stake, around Q2/Q3 2023.
Once the Ethereum mainnet transitions to proof-of-stake, Rinkeby will no longer be an accurate staging environment for mainnet. A list of changes introduced by The Merge that application developers should be aware of is available here. Again, note that these changes will not be deployed to Rinkeby.
Developers who currently use Rinkeby as a staging/testing environment should prioritize migrating to Goerli or Sepolia, and projects who are affected by Ethereum’s transition to proof-of-stake should aim to do so as soon as possible.
Goerli and Sepolia
The two testnets which client developers will maintain post-merge are Goerli and Sepolia.
The Goerli network will merge with the Prater Beacon Chain testnet. A new Beacon Chain has been created to transition Sepolia to proof-of-stake.
Goerli’s Beacon Chain will remain open for users wanting to run a testnet validator. Sepolia will operate with a permissioned validator set, similarly to how some testnets work today. Stakers wanting to test protocol upgrades before they are deployed to mainnet should therefore use Goerli.
Goerli also has a strong community and a lot of existing infrastructure supporting it. Its state is the closest to mainnet, which can be useful for testing smart contract interactions.
Sepolia, on the other hand, is fairly new, meaning its state and history are both quite small. This means the network is quick to sync to and that running a node on it requires less storage. This is useful for users who want to quickly spin up a node and interact with the network directly.
Summary
In brief, Kiln, Ropsten and Rinkeby are out of date. Kiln and Ropsten have already switched to proof-of-stake while Rinkeby will not take this action.
Once The Merge is put into effect on mainnet, Kiln will be discontinued. Ropsten will follow by the end of the year. By Q2/Q3 2023, after Sepolia has completed its transition to proof-of-stake, Rinkeby will be shut down.
Two testnets, Goerli and Sepolia, will be maintained going forward. Goerli is recommended for stakers to test protocol upgrades and developers who want to interact with a large existing state. Sepolia is recommended for users and developers who want a lighter weight chain to sync to and interact with.
