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Available on Testnet today. Testnet finality delays are intentionally short. Mainnet values are published before Mainnet launch.
A transaction passes through three states: soft confirmation, safe, and finalized. A Flashblock preconfirmation arrives before all three. Only finalization makes it irreversible. Only withdrawals to Ethereum wait for the dispute-resolution period. A normal transaction on Whitechain, such as a send, a swap, or a contract call, is included in about one second and reaches finality in under an hour on Testnet.

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Confirmation stages

The 200-millisecond, one-second, and 13-minute figures are protocol timings. The safe delay depends on how often batches are posted, up to about 30 minutes on Testnet. A preconfirmation is the weakest of the four stages; see Flashblocks.

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The transaction lifecycle

  1. Send you submit the transaction and the sequencer receives it.
  2. Soft confirmation the sequencer orders the transaction and includes it in an L2 block, about once per second. Your wallet shows it as complete, but the guarantee is only the sequencer’s word. Because one sequencer orders every transaction, a soft confirmation can still be reordered or dropped before the batch reaches Ethereum. Treat it as fast feedback, not a final receipt.
  3. Safe the sequencer groups transactions into batches, compresses them, and the op-batcher posts them to Ethereum as blobs (EIP-4844). Once that batch is confirmed on Ethereum, your block is safe. Separately, the op-proposer publishes the L2 state root to Ethereum through the DisputeGameFactory contract.
  4. Finalized when the Ethereum block that carries your batch reaches Ethereum finality, about 13 minutes later, your L2 block becomes finalized. From that point the L2 state derives from finalized Ethereum data and cannot be reversed.
An Ethereum reorg does not roll back a finalized L2 block. A shallow reorg can move the safe head: the node re-derives from the canonical Ethereum chain and the affected batch is re-posted. Blocks that reached finality are protected the same way finalized Ethereum blocks are. Whitechain is in Testnet, so historical reorg rates are not yet published. Expected figures are added with Mainnet.

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Flashblocks

Ahead of each full one-second L2 block, the sequencer streams Flashblocks: partial blocks published about every 200 milliseconds. They are powered by Flashbots rollup-boost, which runs a block builder alongside the sequencer. A Flashblock is a preconfirmation. It tells you within about 200 milliseconds that your transaction is included and ordered. That feedback carries the same trust as a soft confirmation, the sequencer’s word, and is not safe or finalized until its batch reaches Ethereum. Apps that read the Flashblocks stream can show sub-second feedback, and the finality stages above are unchanged. The stream is separate from the public RPC, which does not carry it. To read it, request the Flashblocks WebSocket URL from the Whitechain team; see what a node does not provide.

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Withdrawing to Ethereum

Finality makes your L2 state irreversible. Moving assets back to Ethereum takes longer, because a withdrawal must also clear a dispute-resolution period. On Testnet a full withdrawal takes about an hour. On Mainnet a withdrawal takes at least 7 days. Deposits run the other way and are quick: moving funds from Ethereum to Whitechain takes about 2 minutes. See the canonical bridge guide for the steps and exact timing parameters.

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What keeps your funds safe

Whitechain operates the sequencer today, so liveness, whether new blocks are produced, depends on it. Safety rests on Ethereum, but not unconditionally. The mechanisms below hold your funds as long as transaction data stays on Ethereum and an honest challenger disputes any invalid state root.

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Data availability

Every transaction’s data is posted to Ethereum. Anyone can download it and recompute the L2 state, so the sequencer cannot hide or alter a transaction.

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Fault proofs

A proposed state root can be disputed on Ethereum through an on-chain game. The game replays the disputed step in Cannon, a MIPS virtual machine, and the side proven wrong loses its bond. Today that game is permissioned, so only Whitechain’s configured challenger can dispute a root. The design moves toward permissionless challenging, where anyone can take part. A Guardian role can also pause withdrawals or blacklist a game that resolves incorrectly.

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Censorship resistance

If the sequencer refuses your transaction, you can submit it through the OptimismPortal contract on Ethereum. The protocol must then include it within the sequencing window, about 12 hours, or the chain is invalid.