Mikhail Kalinin
Ethereum core developer, architect of The Merge
Mikhail Kalinin is an Ethereum core developer who played a central role in designing the transition mechanism for The Merge — Ethereum's shift from proof-of-work to proof-of-stake in September 2022.
Early Career
Kalinin studied at the Siberian Automobile and Highway Academy, where he focused on computer science. After graduating in 2009, he worked as a Java programmer, finding freelance work through UpWork.
EthereumJ and EtherCamp
In 2015, Roman Mandeleil found Kalinin on UpWork and hired him to work on an Ethereum client written in Java. This client, called EthereumJ, became one of the early alternative Ethereum implementations. Mandeleil went on to found EtherCamp, a hackathon and education provider.
After Mandeleil's departure from the project, Kalinin reached out directly to Vitalik Buterin, who endorsed the EthereumJ client. Kalinin continued development and went on to contribute to early proof-of-stake research, specifically Casper the Friendly Finality Gadget (Casper FFG).
The Merge
Kalinin was the primary author of EIP-3675, which specified the upgrade to replace Ethereum's proof-of-work consensus with the Beacon Chain's proof-of-stake system. He designed the key transition mechanism that allowed the execution layer and consensus layer to merge seamlessly on September 15, 2022.