First published 16 August 2023, the day after mainnet, as the claim window opened. Expanded in October 2026 so the Ethereum-style address is not described as Ethereum, and so the Cosmos path is not described as still the front door. Sei is a proof-of-stake chain aimed at trading. Jayendra Jog and Jeffrey Feng started Sei Labs. SEI pays the fee, is the stake, and is the vote. What is Cosmos (ATOM)? is the hub of the toolkit the chain launched with. Ethereum without the jargon is the contract shape the chain later added. SEI is not ATOM, and it is not ETH.
Pacific-1, the mainnet, opened on 15 August 2023. The launch supply was 10 billion. About 1.8 billion, 18 percent, was unlocked, and the rest was locked on schedules that run for years. The project’s own disclosure says staking rewards are paid from a reserve rather than by minting past 10 billion. A reserve is coins that already existed. A vote can change a reserve. The explorer is the count. A price times 10 billion, in 2023, counted coins the lock had not released.
Two doors, then one
The first contracts were in the Cosmos style. In 2024 an upgrade added an Ethereum-style virtual machine, so the same account could face both. A 2025 vote, SIP-3, pointed the chain at that virtual machine alone. Through 2026 the Cosmos messaging path was turned off. Outbound transfers on it were disabled on 31 July 2026. SEI that had already left on that path is on another chain. It does not come home by itself. A bridge is extra software, not a tunnel.
The EVM chain id is 1329. An address that starts with 0x on Sei is not an Ethereum address. An address that starts with sei1 is the old account format. The wrong network is still the wrong city. Leaving a stake takes 21 days. Staking is a lock and a queue, not a savings account.
The 2023 airdrop is closed. A link that says claim SEI, and asks for a recovery phrase, is not that claim. A wallet signature is not a handshake. Nothing here is an instruction to stake, to bridge, or to buy SEI.
