The Ethereum Foundation announced on September 9, 2022 that the Kiln testnet would be shut down during the week of September 12, with bootnodes and validators switched off permanently. The retirement came days before Ethereum's mainnet completed its transition from proof-of-work (PoW) to proof-of-stake (PoS) on September 15, an upgrade known as The Merge. Kiln's closure was the first full network shutdown in a broader plan to consolidate Ethereum's fragmented testnet infrastructure into two long-term networks: Goerli and Sepolia. That plan had been announced on June 21, 2022, and Ropsten had already completed its own Merge on June 8, 2022, before Kiln's shutdown took effect in September.

The Ethereum Foundation was direct in its guidance to the developer community. "Users and developers should migrate to Goerli and/or Sepolia," the Foundation stated in its shutdown announcement. Kiln had served a narrow, specific purpose. Launched in early 2022, it gave client teams, developers, and infrastructure providers a post-Merge environment to test against before the existing long-standing testnets underwent their own transitions.

Once that work was done, the network was always going to close. The Foundation's farewell was brief: "Farewell Kiln, you've lived up to your name." A kiln is a high-temperature furnace used for firing and hardening materials, making the send-off a fitting one for a testnet that had done its job and burned out on schedule.

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A Planned Consolidation, Not a Surprise

The Kiln shutdown did not happen in isolation. The Ethereum Foundation had flagged the broader testnet rationalisation strategy in a June 21, 2022 announcement, citing fragmented resources and developer confusion.

Ropsten, the oldest Ethereum testnet having run since 2016, completed its own Merge on June 8, 2022 and was placed on a Q4 2022 shutdown schedule. Rinkeby, a geth-only proof-of-authority testnet that was never going to transition to PoS (its client-specific architecture made multi-client compatibility impossible), received a Q3 2023 end-of-life date.

The two surviving networks serve different audiences. Goerli is designed for stakers and protocol-level developers because its state closely mirrors Ethereum mainnet. Sepolia is lighter, syncs faster, and fits the needs of smart contract developers and dApp builders who do not require mainnet-scale state. Both completed their own Merge transitions in September 2022.

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The Merge by the Numbers

The consensus change that Kiln helped test was, by multiple measures, the most consequential upgrade in Ethereum's history. The transition had been in development for approximately seven years, and it drew a characterisation widely used across developer and technology coverage, including by MIT Technology Review on September 15, 2022: "the most complex software upgrade in Ethereum's history."

The Beacon Chain, which became Ethereum's new consensus layer, had been running in parallel to mainnet since December 2020. Notably, the Merge represented the first time in history that a live, operational, large-scale blockchain network changed its entire consensus mechanism without going offline, a feat that set it apart from any prior upgrade of comparable scope.

The energy impact was immediate and dramatic. Pre-Merge, Ethereum consumed roughly 23 million megawatt-hours of electricity per year. Post-Merge figures compiled by the Crypto Carbon Ratings Institute (CCRI) for Consensys showed consumption falling to approximately 2,600 MWh per year, a reduction exceeding 99.988%. Carbon dioxide emissions dropped by 99.992%, from over 11 million tons annually to under 870 tons. Consensys called it "the biggest decarbonization in the history of tech." Post-Merge, Ethereum's annual energy footprint became comparable to fewer than 100 U.S. homes.

On the network side, over 13.1 million ETH had been staked on the Beacon Chain as of late July 2022, before the final transition. Post-Merge staking yield was projected at roughly 6.9 to 7.5% APR, according to Coinbase Institutional research.

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Regional Impact: India and Africa Carry a Migration Burden

The testnet consolidation carried practical consequences for developers outside North America and Europe. India, home to an estimated 6 to 8% of global blockchain developers by end-2022, had a developer community that had largely built documentation and tooling around Ropsten and Rinkeby over the preceding years. For context, North America and the EU each represented approximately 29% of global blockchain developers as of end-2022, making India's share meaningful but concentrated in a community that relied heavily on resources tied to the networks being retired.

Tutorial content, bootcamp curricula, and open-source documentation in Hindi, Tamil, and other regional languages had been built around those networks over years. The shift to Goerli and Sepolia created a short-term knowledge gap, particularly for newer or independent developers without consistent access to up-to-date English-language resources.

The energy story landed differently in India, where the power grid remains heavily coal-dependent. Proof-of-work Ethereum had provided ammunition to regulators sceptical of crypto's environmental cost. The reduction of more than 99.988% in energy consumption (as confirmed by CCRI post-Merge data compiled for Consensys) directly addressed that criticism and opened a different conversation for developers making institutional arguments for Ethereum adoption.

In Africa, where blockchain developers represented approximately 4% of the global total in 2022 but accounted for roughly 20% of developers "actively learning" the technology (the highest proportion worldwide), the testnet migration placed an outsized burden on a community still building foundational skills. Nigeria and Kenya, both significant Web3 hubs on the continent, had developer communities relying on Remix, Hardhat, and Truffle, tools that had Ropsten and Rinkeby baked into default configurations. African blockchain startup funding had surged 429% year-on-year in 2022 to $474 million, meaning this infrastructure shift arrived at a moment of rapid ecosystem growth.

The move to proof-of-stake also changed participation dynamics in regions where reliable electricity and hardware access are genuine barriers. Mining under PoW required both. Becoming a solo validator under PoS still requires 32 ETH (approximately $51,000 at the time of the Merge), but liquid staking protocols such as Lido and Rocket Pool lower that threshold significantly. For developers and communities across South Asia and Africa, the post-Merge network represents a structurally more accessible system, even if the documentation gap created short-term friction for those navigating the transition.