Sei

Sei is a high-performance Layer 1 blockchain specifically optimised for trading and exchange applications, co-founded by Jeffrey Feng and Jayendra Jog and launched on mainnet in August 2023. Originally built on the Cosmos SDK, Sei evolved through multiple versions with dramatically different technical goals at each stage. Sei V1 (2023) shipped as a specialised CosmWasm-based trading L1 with an on-chain order matching engine, native price oracles, and front-running protection primitives designed to make orderbook-style DEXs viable at low latency. In late 2024 Sei V2 launched, introducing a parallelised EVM — the first mainnet EVM chain to process independent transactions concurrently — bringing full Ethereum compatibility and Solidity-native tooling to the network while retaining the underlying performance characteristics.

The network achieves block times of around 400 milliseconds with single-block finality, making it one of the fastest blockchains in production. Sei's architecture combines optimistic concurrency control (transactions are executed in parallel, and only conflicts trigger re-execution), a twin-turbo consensus derived from Tendermint with pipelining optimisations, and an intent-oriented execution environment. The chain supports both EVM (Solidity) and CosmWasm smart contracts natively, giving developers flexibility to bring Ethereum-native applications or write Rust-based contracts targeting the CosmWasm module.

Sei's parallelised execution model processes independent transactions simultaneously across multiple threads. This means a DEX trade and an NFT mint happening at the same time don't compete for the same processing resources, and the chain's effective throughput scales with the number of CPU cores available to validators rather than being bottlenecked on serial execution. Combined with native price oracles that push validator-signed price data directly into the consensus layer, Sei delivers a trading experience that aims to rival centralised exchanges in speed while maintaining permissionlessness. The Sei team has also introduced Autobahn, a new consensus proposal that would push finality to under 400ms and dramatically increase per-second transaction capacity.

Sei's ecosystem has grown through partnerships with major DeFi teams and gaming projects. Notable native protocols include DragonSwap (DEX), Yaka Finance (DEX aggregator), Jellyverse, and various NFT marketplaces. The chain has attracted significant venture backing and remains one of the more actively developed newer L1s heading into 2026.