> ## Documentation Index
> Fetch the complete documentation index at: https://l2docs.whitechain.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Legacy L1 migration reference

> How the legacy Whitechain L1 migrates to the L2: what state carries over, the snapshot block, the read-only period, and the hostname cut-over.

<Note>
  This page documents the legacy Whitechain Layer 1 (L1), mainnet chain ID `1875`. The L1 is live and producing blocks. It is a separate chain from the Whitechain Layer 2 (L2) documented in the rest of these docs, and it migrates to the L2 at L2 Mainnet launch. For the full migration plan, sunset stages, and milestones, see [Migration to L2](/learn/general/migration).
</Note>

This page covers the L1 to L2 migration from the perspective of the legacy L1. Migration has not happened yet. The L1 mainnet produces blocks and accepts transactions today, and it stops at L2 Mainnet launch, on a date that is not yet announced. For the full migration narrative, the technical comparison table, and the current network details, see [Migration to L2](/learn/general/migration).

## What gets migrated

The complete state of the Whitechain L1 mainnet becomes the OP Stack L2 genesis:

* All account balances, for both externally owned accounts and contracts
* All smart contract code and storage slots
* Nonce values for every account

No user action is required. Addresses on the L1 map one to one to the same addresses on the L2, so balances and contract identities are preserved. Transaction history and event logs are not migrated, and pending mempool transactions never execute.

Migration applies to Mainnet only. The L1 testnet, chain ID `2625`, is not migrated. It is superseded by Whitechain Sepolia, chain ID `1874`, which starts from its own genesis. See [Scope of the migration](/learn/general/migration#scope-of-the-migration).

## L1 state at the cut-over

The L1 sequencers stop at the snapshot block, which is the last block the L1 produces. The full state at that block is exported and transformed into the L2 genesis.

After the snapshot block the L1 enters a read-only period. The L1 explorer and the L1 JSON-RPC API answer read methods against L1 state up to the snapshot block, and they refuse the methods that submit a transaction. No new L1 transaction is possible. The length of the read-only period is not yet announced. See [What read-only mode means](/learn/general/migration#what-read-only-mode-means).

The snapshot block number and timestamp are published with the L2 Mainnet launch date. No date is announced yet. See [Deadlines](/learn/general/migration#deadlines).

## Endpoints at the cut-over

At L2 Mainnet launch the L1-linked hostnames are reassigned to the L2, and the L1 services move to `legacy` hostnames.

| Service     | Hostname today                   | Hostname after L2 Mainnet launch                                                                                    |
| ----------- | -------------------------------- | ------------------------------------------------------------------------------------------------------------------- |
| L1 website  | `https://whitechain.io`          | `https://legacy.whitechain.io`                                                                                      |
| L1 explorer | `https://explorer.whitechain.io` | `https://legacy-explorer.whitechain.io`                                                                             |
| L1 JSON-RPC | `https://rpc.whitechain.io`      | Legacy read-only RPC hostname, published in the [Network reference](/learn/network/reference) before Mainnet launch |

`whitechain.io`, `explorer.whitechain.io`, and `rpc.whitechain.io` serve the L2 from the cut-over onward. Confirm which chain an endpoint serves by calling `eth_chainId`: the legacy L1 mainnet reports chain ID `1875` (hex `0x753`). See [Endpoint and domain changes](/learn/general/migration#endpoint-and-domain-changes).

## What replaces the L1 components

| L1 component                                                | L2 replacement                                                                |
| ----------------------------------------------------------- | ----------------------------------------------------------------------------- |
| Clique PoA consensus, single validator operated by WhiteBIT | OP Stack sequencer, initially operated by WhiteBIT                            |
| Fixed 10 gwei gas price                                     | EIP-1559 with OP Stack parameters                                             |
| 2 second block time                                         | 1 second block time, with Flashblocks about every 200 ms                      |
| Single-block finality on L1                                 | Sequencer confirmation first, then finalization on Ethereum                   |
| Third-party bridge to Ethereum                              | Native OP canonical bridge to Ethereum alongside existing third-party bridges |
| PoA block rewards                                           | Periodic distribution via smart contract                                      |

## L1 decommissioning

The L1 is decommissioned permanently after the read-only period. Its explorer and JSON-RPC API shut down, and L1 transaction history is no longer reachable from any Whitechain endpoint.

<Warning>
  L1 transaction history and event logs are not migrated to the L2. Export the L1 history your systems need before decommissioning, from `https://explorer.whitechain.io` while the L1 is live and from `https://legacy-explorer.whitechain.io` after the cut-over.
</Warning>

For why Whitechain is moving to L2 and the broader technical comparison, see [Migration to L2](/learn/general/migration).