Sei (SEI)

What Sei is

Sei is an Ethereum-compatible layer 1 built around parallel transaction execution. Its documentation describes it as "the first parallelized EVM blockchain delivering unmatched scalability and speed," running 400 millisecond blocks with roughly 100 megagas per second of throughput and full Ethereum tooling compatibility (source: Sei documentation, read September 2026). SEI is the network's gas, staking and governance asset.

The pitch is compatibility without the usual tradeoff. Standard Solidity contracts deploy without modification, but transactions that touch independent state run concurrently rather than one after another. Mainnet is chain ID 1329, testnet is 1328, and gas is paid in SEI with 18 decimals.

How it works

Three subsystems produce the performance the documentation claims. Twin Turbo Consensus delivers sub-second blocks and fast finality. The Parallelization Engine provides multi-core execution and transaction classification. SeiDB provides optimized state access and concurrent operations.

Classification is the part that makes parallel execution safe. Transactions writing to shared state must still be serialized; transactions touching disjoint state can run at once. The documentation puts the practical consequence plainly: transactions touching independent state are parallelized automatically, while shared-state writes are serialized.

Sei's EVM tracks the Pectra feature set, with one deliberate omission: blob transaction support is not included.

Two operational facts are worth knowing before you move assets. Inter-Blockchain Communication is disabled in both directions. Under SIP-03, governance proposals 116 and 120 set the IBC module's inbound parameter to false, and proposal 121 set the outbound parameter to false on 31 July 2026. No asset can be bridged into or out of Sei over IBC. Separately, the tokenfactory module is unsupported for new work, and the documentation directs developers to use erc 20 for new fungible tokens.

Staking follows the Cosmos pattern with one significant exception. Delegated stake has "a 21-day un-bonding period during which the tokens are not earning rewards and cannot be transferred." Redelegating bars the new validator "from further re-delegations for 21 days," and a delegator may "re-delegate a maximum of 7 times simultaneously." The exception is that, in the documentation's words, "there is no slashing of funds in Sei."

Supply and tokenomics

Sei's documentation covers the protocol in detail and does not publish token supply figures. What it does specify precisely is the network's performance envelope and the fee design of its next architecture.

RampAtlas could not source SEI's total supply, allocation or inflation schedule from Sei's own documentation, which covers architecture and operations rather than token distribution. Those figures are recorded here as unpublished rather than restated from secondary sources.

History

The current network is the second act. The first delivered the parallelized EVM with 400 millisecond blocks. Sei Giga, described in the documentation as "the first Multi-Proposer EVM Layer 1," is a rebuild of consensus, execution and storage together.

Giga's consensus protocol is called Autobahn, and it separates data dissemination from ordering. Each validator maintains a lane, defined as an append-only, hash-chained sequence of transaction batches, and proposes data in parallel. Data is certified when validators collect f + 1 matching votes in a replica model of n = 3f + 1, producing a Proof of Availability. A "cut," a vector of all lanes' certified tips, is committed once and finalizes transactions across every lane at once. The documentation reports one committed cut per 1.5 network round trips under pipelining, against three rounds in Tendermint.

Execution moves off the critical path. Giga separates ordering finality, where consensus fixes the sequence, from state attestation finality, where a later block carries "two-thirds voting-power signatures over per-block lattice-hash divergence digests." Execution itself uses Block-STM optimistic concurrency, re-executing only transactions whose reads collided with an earlier write and falling back to sequential execution after ten retries.

Storage drops the Merkle state root entirely. Giga uses LtHash, a homomorphic lattice hash that updates incrementally in any order, with per-block Block Update Digests and aggregated SuperBUDs for long-range proofs. The tradeoff is stated openly: Giga will not support EIP-4844 blob transactions, PREVRANDAO, Merkle state roots or fixed block gas limits.

Fees under Giga are three-part: an execution fee using an eip 1559-style dynamic base fee, an ordering fee acting as a priority fee under a deterministic merge rule, and a distribution fee that prices duplicate submissions for censorship resistance.

As of specification version 6.6 in August 2026, Autobahn is implemented but disabled until network activation, and the Ares execution client has become the default path.

Risks and what to watch

Architectural transition risk is the largest technical exposure. Giga replaces consensus, execution and state commitment at once, and its headline numbers come from an internal devnet rather than from production. New consensus code carries new failure modes.

The absence of slashing is a design choice with two faces. It removes a real risk for delegators, and it removes a penalty that other proof-of-stake networks rely on to deter validator misbehavior. Watch how validator accountability is enforced without it.

Token opacity is a genuine problem for a holder. Without a published supply schedule in the project's own documentation, future issuance cannot be verified from a primary source.

Bridge risk is concentrated by the IBC decision. With the Cosmos-native path closed, assets reach Sei through other bridges, and each of those carries its own trust assumptions.

Compatibility gaps are worth checking before deploying. No blob transactions today, and no PREVRANDAO or Merkle state roots under Giga, means some Ethereum patterns will not port unchanged.

Frequently asked questions

What makes Sei different from other EVM chains?

Parallel execution. Transactions touching independent state run concurrently across cores, while shared-state writes are serialized, with 400 millisecond blocks and roughly 100 megagas per second of throughput.

Does Sei slash staked tokens?

No. The documentation states there is no slashing of funds in Sei. Unbonding still takes 21 days, during which tokens earn no rewards and cannot be transferred.

Can you bridge assets to Sei over IBC?

No. Governance disabled inbound IBC under proposals 116 and 120, and disabled outbound IBC under proposal 121 on 31 July 2026.

What is Sei Giga?

The next architecture, described as the first multi-proposer EVM layer 1. It uses Autobahn consensus with per-validator lanes, asynchronous execution, Block-STM parallelism and lattice-hash storage in place of a Merkle state root.

Where can you buy Sei?

SEI is listed across many centralized venues. See where to buy Sei for availability in your jurisdiction and Exchanges to compare fees and staking support.