> ## 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.

# Frequently asked questions

> Common questions about Whitechain: what it is and who runs it, Mainnet status, WBT and gas fees, transaction finality, public RPC endpoints and rate limits, contract deployment, wallets, bridging, withdrawals, migration, and grants.

<Note>
  Available on Testnet today (Whitechain Sepolia, chain ID `1874`). Mainnet is not yet live; its chain ID, endpoints, and launch date are published before Mainnet launch.
</Note>

## General

<AccordionGroup>
  <Accordion title="What is Whitechain, and who is behind it?">
    Whitechain is powered by WhiteBIT, one of the largest centralized exchanges in Europe, with more than 5 million active users. It is an EVM-compatible Layer 2 built on the OP Stack. It settles on Ethereum through blob data availability and uses WBT (WhiteBIT Coin) as the native gas token. WhiteBIT operates the sequencer at launch and is the canonical issuer of WBT. See [Introduction to Whitechain](/learn/general/what-is-whitechain).
  </Accordion>

  <Accordion title="Is Mainnet live yet, or only the testnet?">
    The L2 is live on Testnet today, as Whitechain Sepolia (chain ID `1874`). Mainnet is not yet live. Its chain ID, endpoints, and launch date are published before Mainnet launch. Build and test on Whitechain Sepolia now, then move to Mainnet at launch. See the [Network reference](/learn/network/reference).
  </Accordion>

  <Accordion title="What does it mean that Whitechain is an OP Stack L2?">
    The OP Stack separates execution, data availability, and settlement into distinct layers. Every transaction's data is published and settled on Ethereum, so Whitechain inherits Ethereum's security and data-durability guarantees instead of carrying its own. The chain keeps full EVM compatibility, so any contract or toolchain that works on Ethereum works on Whitechain. The OP Stack also underlies Base, Optimism, and the wider Superchain, which gives Whitechain shared tooling and a path toward decentralized sequencing.
  </Accordion>

  <Accordion title="What happens to my legacy L1 balances and contracts at migration?">
    Nothing is required from you. The legacy L1 is live and producing blocks today. At L2 Mainnet launch the full L1 state migrates into the L2 genesis automatically. Native WBT balances are preserved to the wei, and contracts keep their bytecode, storage, nonces, and addresses. ERC-20 and other token balances live in contract storage, so they migrate with it. Transaction history and pending mempool transactions are not carried over; only final state is. After the snapshot block the L1 answers read methods only, and it is decommissioned later, so export any historical data you need before then. See [Migration to L2](/learn/general/migration).
  </Accordion>

  <Accordion title="Is there a migration deadline, and what do I have to do before it?">
    Holders have no deadline, because holders have no task to complete. There is nothing to claim, swap, or unlock. Integrations have milestones to plan against: the L1 snapshot block, L2 Mainnet launch, the domain cut-over, the L1 read-only period, and L1 decommissioning. No date for any of them is announced yet. Whitechain publishes migration dates on [X](https://x.com/Whitechain_io), in the [Whitechain Telegram channel](https://t.me/Whitechain_io), and on the migration page. See [Deadlines](/learn/general/migration#deadlines).
  </Accordion>

  <Accordion title="I run an exchange, wallet, or indexer on the legacy L1. What has to change?">
    Your users' balances migrate on their own; your connection settings do not. Repoint to the L2 chain ID, RPC URL, and explorer, stop crediting L1 deposits at the snapshot block, and export any L1 history your systems need before decommissioning. Contracts need no redeployment.

    The hostnames also change. `rpc.whitechain.io` and `explorer.whitechain.io` serve the legacy L1 (chain ID `1875`) today and serve the L2 after the cut-over. The L1 explorer moves to `https://legacy-explorer.whitechain.io`, the L1 website moves to `https://legacy.whitechain.io`, and the legacy read-only RPC hostname is published in the [Network reference](/learn/network/reference) before Mainnet launch. Confirm which chain an endpoint serves with `eth_chainId` rather than by hostname. See [Endpoint and domain changes](/learn/general/migration#endpoint-and-domain-changes) and [Integrations and service operators](/learn/general/migration#integrations-and-service-operators).
  </Accordion>

  <Accordion title="How fast is a transaction, and when is it irreversible?">
    Blocks arrive every second, and Flashblock preconfirmations arrive about every 200 ms. Those are the sequencer's word only. Your transaction becomes safe when its batch is confirmed on Ethereum, up to about 30 minutes on Testnet, and finalized about 13 minutes after that. Only finalization is irreversible. See [Transaction finality](/learn/network/transaction-finality).
  </Accordion>

  <Accordion title="Who runs the sequencer, and what if it censors or drops my transaction?">
    WhiteBIT operates the single sequencer today, so block production depends on it. If the sequencer refuses your transaction, you can submit it through the `OptimismPortal` contract on Ethereum. The protocol must include it within the sequencing window, about 12 hours, or the chain is invalid. Transaction data is posted to Ethereum, so the sequencer cannot hide or alter a transaction. See [What keeps your funds safe](/learn/network/transaction-finality#what-keeps-your-funds-safe).
  </Accordion>

  <Accordion title="Where do I get help with the migration?">
    For WBT held on the exchange, use WhiteBIT support. For integration, node, or contract questions, use the [Whitechain Discord](https://discord.gg/eZwjxwNsU). Migration dates are announced on [X](https://x.com/Whitechain_io) and in the [Whitechain Telegram channel](https://t.me/Whitechain_io). Support never asks for your seed phrase, private key, or a wallet signature to complete a migration step. See [Where to get help](/learn/general/migration#where-to-get-help).
  </Accordion>
</AccordionGroup>

## Fees and WBT

<AccordionGroup>
  <Accordion title="What token do I pay gas in, and why WBT instead of ETH?">
    You pay gas in WBT, the native gas token, configured as the OP Stack custom gas token with 18 decimals. Every fee on Whitechain is paid in WBT, regardless of network, so you need a WBT balance to send any transaction. WBT is the native asset of Whitechain and the token of the WhiteBIT ecosystem, so a single asset covers on-chain gas and exchange utility. See [Network fees](/learn/network/network-fees).
  </Accordion>

  <Accordion title="How much does a typical transaction cost?">
    A fee has two parts: the L2 execution fee (gas used times the gas price) and the L1 data fee for publishing your transaction to Ethereum. At the 5 gwei base-fee floor, a plain WBT transfer of 21,000 gas costs about 0.000105 WBT to execute, well under one cent at \$50 per WBT. Deploying a small contract costs about 0.0006 WBT, roughly three cents at that price. The L1 data fee is added on top and tracks Ethereum's gas price, so totals rise when Ethereum is busy. See [Network fees](/learn/network/network-fees).
  </Accordion>

  <Accordion title="How do I get WBT for gas on Mainnet?">
    Buy WBT on [WhiteBIT](https://whitebit.com), through the Convert tool or a fiat deposit, then withdraw it to your Whitechain address. You can also bridge ERC-20 WBT from Ethereum mainnet. After Mainnet launch, WhiteBIT users withdraw WBT directly to Whitechain L2 from the exchange UI, with no third-party bridge in between. See [Getting WBT](/learn/general/get-wbt).
  </Accordion>

  <Accordion title="How do I get testnet WBT, and what is the faucet chain ID?">
    Claim test WBT from the faucet at [faucet.testnet.whitechain.io](https://faucet.testnet.whitechain.io). Add Whitechain Sepolia to your wallet first, using chain ID `1874` and the RPC at `https://rpc.testnet.whitechain.io/`. Sign in with a GitHub account at least 30 days old. The standard drip is 0.5 WBT per 24-hour rolling window. Test WBT has no real value and cannot be bridged to mainnet. See [Faucet](/learn/get-started/get-testnet-wbt).
  </Accordion>

  <Accordion title="Why did my balance drop by more than the fee shown on the explorer?">
    The explorer may show only the L2 execution fee. The L1 data fee for publishing your transaction to Ethereum is charged on top of it, and the difference is that fee. Both parts are always charged. See [Network fees](/learn/network/network-fees).
  </Accordion>

  <Accordion title="Do I pay for a transaction that fails?">
    Yes. The network does the work up to the point of failure, so you pay for the gas used, and both fee parts are charged. Nothing is refunded. Set a sufficient gas limit so a contract call does not run out partway through. See [Network fees](/learn/network/network-fees).
  </Accordion>

  <Accordion title="How predictable are gas prices?">
    The L2 base fee follows EIP-1559 with elasticity 6 and denominator 250, so it moves by at most 2% per block and never drops below 5 gwei. The L1 data fee is the variable part: it tracks Ethereum's base fee and blob base fee, so your total rises when Ethereum is busy. See [Fee parameters](/learn/network/network-fees#fee-parameters).
  </Accordion>
</AccordionGroup>

## For developers

<AccordionGroup>
  <Accordion title="Do my existing Ethereum contracts work without changes?">
    Yes. Whitechain keeps full EVM compatibility, so any contract or toolchain that runs on Ethereum runs on Whitechain without modification. Deploy with Hardhat, Foundry, Remix, or any Ethereum library. See [Deploy a contract](/learn/get-started/deploy-a-contract).
  </Accordion>

  <Accordion title="What are the RPC endpoints and chain IDs for Mainnet and Sepolia?">
    Whitechain Sepolia is live now; Mainnet parameters are published before Mainnet launch.

    | Network            | Chain ID                             | RPC                                  | Explorer                                                                 |
    | ------------------ | ------------------------------------ | ------------------------------------ | ------------------------------------------------------------------------ |
    | Mainnet            | TBD, published before Mainnet launch | TBD, published before Mainnet launch | TBD, published before Mainnet launch                                     |
    | Whitechain Sepolia | `1874`                               | `https://rpc.testnet.whitechain.io`  | [explorer.testnet.whitechain.io](https://explorer.testnet.whitechain.io) |

    Whitechain Sepolia also exposes a WebSocket endpoint at `wss://rpc.testnet.whitechain.io/ws`. See the [Network reference](/learn/network/reference).
  </Accordion>

  <Accordion title="How do I deploy and verify a contract?">
    Whitechain Sepolia is a standard EVM network, so you add it by chain ID and RPC URL and need no Whitechain-specific plugin. Deploy with your usual toolchain, then verify the source on the [explorer](https://explorer.testnet.whitechain.io) or [Sourcify](https://sourcify.dev). The [Deploy with Hardhat](/build/deploy/deploy-with-hardhat) guide covers the full deploy-and-verify flow; [Remix](/build/deploy/deploy-with-remix) and [Foundry](/build/deploy/deploy-with-foundry) guides are also available.
  </Accordion>

  <Accordion title="Which network should I use before Mainnet?">
    Use Whitechain Sepolia (chain ID `1874`), the public test environment for dapp deployment, integration testing, and claiming test WBT from the faucet. See [Connect to Whitechain Sepolia](/learn/get-started/connect-wallet).
  </Accordion>

  <Accordion title="Which wallets work with Whitechain?">
    Any standard EVM wallet. Whitechain documents MetaMask, Rabby, and Reown (formerly WalletConnect) for everyday signing, and Safe for multisig treasury and admin operations. No Whitechain-specific plugin exists, because you add the network by chain ID and RPC URL. See [Wallets](/build/wallet/wallets).
  </Accordion>

  <Accordion title="Do I need a Whitechain-specific SDK?">
    No. Use the Ethereum libraries you already use. viem includes OP Stack support, so it returns the L1 data fee and keeps working across network upgrades without edits to your code. See [Use viem with Whitechain](/build/dapps/use-viem).
  </Accordion>
</AccordionGroup>

## Public RPC and infrastructure

<AccordionGroup>
  <Accordion title="Is the public RPC rate limited?">
    Yes, per client IP address. You get 50 requests per second, plus a burst allowance of 500 requests above that. When you exceed it, the endpoint returns HTTP `429 Too Many Requests` with a `Retry-After` header. The limiter counts each HTTP request, so batching several calls into one request helps. See [Public RPC endpoints](/learn/network/reference#public-rpc-endpoints).

    | Property                         | Value                                                    |
    | -------------------------------- | -------------------------------------------------------- |
    | Sustained rate                   | 50 requests per second per client IP                     |
    | Burst allowance                  | Up to 500 requests above the sustained rate              |
    | What the limit counts            | Each HTTP request, not each JSON-RPC call inside a batch |
    | Status code when you are limited | `429 Too Many Requests`                                  |
    | Retry hint                       | `Retry-After: 1` header on every `429` response          |
    | WebSocket limits                 | Published once they are finalized                        |
  </Accordion>

  <Accordion title="Do I need an API key for the public RPC?">
    No. The public RPC and WebSocket endpoints need no API key and no IP allowlist. Reads and writes are open to any client, subject to the limits above.
  </Accordion>

  <Accordion title="What happens when I hit the rate limit, and how should my client react?">
    The endpoint returns HTTP `429 Too Many Requests` with a `Retry-After` header. Retry with exponential backoff, starting from the `Retry-After` value. A client that retries immediately stays above the limit and keeps failing. Batch related calls into one JSON-RPC request, because the limiter counts one HTTP request per batch. Subscribe to `newHeads` over WebSocket instead of polling `eth_blockNumber`, and cache receipts and finalized blocks on your side. See [Working within the limits](/learn/network/reference#working-within-the-limits).
  </Accordion>

  <Accordion title="Are there third-party public RPC endpoints for Whitechain?">
    Not yet. Whitechain is evaluating partnerships with commercial RPC providers, and partner endpoints are published in the [Public RPC endpoints](/learn/network/reference#public-rpc-endpoints) table when they go live. Until then, `https://rpc.testnet.whitechain.io` and `wss://rpc.testnet.whitechain.io/ws` are the only public endpoints for Whitechain Sepolia. Treat any other endpoint claiming to serve chain ID `1874` as unofficial.
  </Accordion>

  <Accordion title="Is there a WebSocket endpoint, and can I subscribe to new blocks?">
    Yes. Whitechain Sepolia exposes `wss://rpc.testnet.whitechain.io/ws`. It serves the standard Ethereum JSON-RPC API and supports `eth_subscribe`, including `newHeads`, `logs`, and `newPendingTransactions`. Reuse one connection for multiple subscriptions rather than opening a connection per query. See [WebSocket and subscriptions](/learn/network/testnet#websocket-and-subscriptions).
  </Accordion>

  <Accordion title="Can I read the Flashblocks stream from the public RPC?">
    No. The Flashblocks 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 [Flashblocks](/learn/network/transaction-finality#flashblocks).
  </Accordion>

  <Accordion title="My workload needs more than the public limits. What are my options?">
    Run your own node. The stack is a pair of services, `op-reth` and `op-node`, and ships three profiles: `full-snap-node` (recommended default), `full-node`, and `archive-node`. Archive is the one required for historical tracing and `eth_call` at old blocks. Your node holds no Whitechain keys and forwards `eth_sendRawTransaction` to the public RPC. See [Node operators](/operate/run-a-node/overview).
  </Accordion>

  <Accordion title="Is the block explorer API public, and is it rate limited?">
    Yes to both. Whitechain uses Blockscout, and its API is public, read-only, and needs no API key. It is rate limited per IP, so batch related lookups and cache results. For sustained querying across full chain history, run your own indexer or Blockscout instance. See [Block explorer overview](/build/block-explorer/overview).
  </Accordion>

  <Accordion title="How do I check whether an endpoint is down or I am being limited?">
    Check [status.whitechain.io](https://status.whitechain.io/) for the RPC, explorer, and faucet. A `429` response is a rate limit on your side, not an outage, and it clears once your request rate drops.
  </Accordion>
</AccordionGroup>

## Bridging and withdrawals

<AccordionGroup>
  <Accordion title="How do I move assets between Ethereum and Whitechain?">
    Use the OP Stack canonical bridge. Deposits from Ethereum to Whitechain arrive on L2 in about 2 minutes. For an ERC-20 token, you approve the L1 standard bridge and call `depositERC20`; the L2 token must already be deployed. Native WBT cannot go through the canonical bridge, because Whitechain runs in custom gas token mode: use the faucet on testnet, and the liquidity portal on mainnet. You can also move WBT through WhiteBIT deposits and withdrawals. See the [OP Stack canonical bridge](/build/bridge/bridge-assets).
  </Accordion>

  <Accordion title="How long do L2-to-Ethereum withdrawals take to finalize?">
    On testnet a full withdrawal takes about an hour, because the dispute-resolution delays are intentionally shortened. On mainnet it takes minimum 7 days. This delay is enforced by the protocol and cannot be skipped, so plan treasury and time-sensitive flows accordingly. Deposits run the other way in about 2 minutes. See [Transaction finality](/learn/network/transaction-finality).
  </Accordion>

  <Accordion title="Why can I not send native WBT through the canonical bridge?">
    Whitechain runs in OP Stack custom gas token mode, where the native token is WBT instead of ETH. The canonical bridge does not carry the native gas token in that mode. Use the faucet on testnet, the liquidity portal on mainnet, or WhiteBIT deposits and withdrawals. ERC-20 tokens do go through the canonical bridge. See [OP Stack canonical bridge](/build/bridge/bridge-assets).
  </Accordion>

  <Accordion title="Can I speed up a withdrawal, or cancel one?">
    No. The dispute window is enforced by the protocol on Ethereum, so no fee or support request shortens it. A withdrawal is proven and finalized in two steps, and it cannot be cancelled once proven. Plan treasury flows around the 7-day minimum on mainnet. See [Transaction finality](/learn/network/transaction-finality).
  </Accordion>

  <Accordion title="Can WhiteBIT users withdraw WBT directly to L2 without a third-party bridge?">
    After Mainnet launch, yes. WhiteBIT users withdraw WBT directly to Whitechain L2 from the exchange UI, with no third-party bridge in the path. New users land on Whitechain with WBT in their wallet through the exchange flow they already use. See [Getting WBT](/learn/general/get-wbt).
  </Accordion>
</AccordionGroup>

## For projects

<AccordionGroup>
  <Accordion title="Is there ecosystem or grant funding, and how is it distributed?">
    The Whitechain Foundation runs a Grants Program with financial, marketing, and technical support for projects building on Whitechain. Grants are distributed via vesting rather than lump sums, which aligns funding with delivery milestones. See the [Whitechain Grants Program](https://whitechain.io/grants) and [For project partners](/build/ecosystem/for-partners).
  </Accordion>
</AccordionGroup>

## Related

* [Introduction to Whitechain](/learn/general/what-is-whitechain)
* [Network reference](/learn/network/reference)
* [Public RPC endpoints and rate limits](/learn/network/reference#public-rpc-endpoints)
* [Whitechain Sepolia full parameters](/learn/network/testnet)
* [Network fees](/learn/network/network-fees)
* [Transaction finality](/learn/network/transaction-finality)
* [Getting WBT](/learn/general/get-wbt)
* [Migration to L2](/learn/general/migration)
* [Wallets](/build/wallet/wallets)
* [Block explorer overview](/build/block-explorer/overview)
* [Node operators](/operate/run-a-node/overview)
* [OP Stack canonical bridge](/build/bridge/bridge-assets)