Migrating Your App to OKX X Layer: Contracts, Frontend, and Acceptance

OKX

21 October 2026

Migrating your app to X Layer — the contract-layer workload depends on which chain you originally deployed on. X Layer is an EVM-compatible Layer 2, so contracts written in Solidity usually don't need code changes. What changes is the deployment configuration: RPC, Chain ID, and gas token. The real extra work is on the frontend: wallet network switching, address format compatibility, and the choice between X Layer's unique XKO-prefixed addresses and standard 0x addresses. The acceptance standard is not "deployment succeeded" but that a user can complete a full operation loop on X Layer.

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Contracts: Change the Config and Deploy, but Don't Use the Wrong Network

X Layer mainnet's Chain ID is 196, the gas token is OKB, and the RPC endpoint can be https://rpc.xlayer.tech. The testnet's Chain ID is 1952, and the RPC is https://testrpc.xlayer.tech/terigon. If you fill in these two numbers incorrectly when configuring Truffle, Hardhat, or Foundry, deployment will fail directly or be sent to the wrong chain.

The official documentation provides deployment tutorials for three mainstream tools. Taking Hardhat as an example, in the networks configuration of hardhat.config.js, point the url to the testnet RPC, fill in the deployment private key in accounts, and then run the deployment script. Truffle's configuration is similar: you need to create a .secret file to store the mnemonic, point the provider to the testnet RPC, and set network_id to 1952. Foundry uses the forge create command, passing in --rpc-url and --private-key to deploy.

One boundary to keep in mind: if you used non-EVM-compatible features on Polygon or Ethereum mainnet (such as specific precompiled contracts), you need to separately confirm whether X Layer supports them before migrating. The official documentation does not list compatibility differences one by one. The safest approach is to run the complete contract logic on the testnet, not just verify that deployment succeeded.

Frontend: XKO Addresses Are the Biggest Variable

X Layer introduces an XKO-prefixed address that coexists with the standard 0x EVM address. OKX's official FAQ explains that XKO addresses are meant to make it easier for users to identify the X Layer network and reduce the risk of address confusion when copying and pasting. It does not replace the 0x address; both point to the same account.

The impact on the frontend is very specific. Currently, DApps automatically use 0x addresses when connecting, and XKO addresses are not yet supported by all ecosystem applications. If your frontend needs to display user addresses, receive transfers, or do address validation, continuing to use 0x addresses is the safer choice while XKO integration is not yet widespread. OKX's own FAQ also recommends that products that do not support XKO should continue using 0x addresses, which does not affect asset security or transfer functionality.

If your frontend has previously only handled 0x addresses, you don't need to do extra adaptation for XKO, but you need to know that users may see XKO-format addresses in the OKX wallet and may copy them to you. If your address validation logic only accepts addresses starting with 0x, it will report an error when users submit an XKO address. This is not a bug; it's a format mismatch. How to handle it depends on your product decision: either prompt users on the frontend to use 0x addresses, or add XKO-to-0x conversion logic (the official side has not published a conversion interface, so you need to handle it yourself).

Wallet network switching is another must-do. When users switch from other chains to X Layer, your frontend needs to be able to trigger wallet_addEthereumChain or wallet_switchEthereumChain, passing in a chainId of 0xc4 (196 in hexadecimal). If the user's wallet does not have X Layer preconfigured, you need to add the network first, with parameters including chainName, rpcUrls, nativeCurrency (OKB, 18 decimals), and blockExplorerUrls.

Acceptance: Break It Down by Stage, Don't Treat "Deployment Succeeded" as the Finish Line

The completion standard for contract deployment is that the transaction is confirmed on the X Layer explorer. The testnet explorer is web3.okx.com/explorer/x-layer-testnet, and the mainnet explorer is web3.okx.com/explorer/x-layer. After getting the transaction hash, check it on the explorer. Only when you see the contract address and a successful status is deployment complete. The "Deployed to" output in the Truffle or Hardhat terminal is only local feedback; on-chain confirmation is another matter.

The completion standard for frontend connection is that users can complete a read and write operation on the X Layer network. Specifically: the wallet successfully switches to Chain ID 196 (or 1952), the frontend can read contract state (such as querying a view function), and then can initiate a write transaction and see confirmation on the explorer. Just seeing "Connected" is not enough. Connected does not mean the network is correct, and a correct network does not mean the contract call can go through.

Acceptance of the complete loop requires an operation involving value transfer. For example, a user deposits tokens, the contract records the balance, and the user can query the amount they deposited. This step will expose parameter format issues between the frontend and the contract, gas estimation issues, and the order of token approval (approve) and actual transfer (transferFrom). X Layer's gas is paid in OKB. If the user's wallet has no OKB, the transaction will fail, and the frontend needs to be able to recognize this situation and give a clear prompt, rather than letting users guess the reason from a generic "transaction failed" message.

An Easily Overlooked Migration Cost

If your application depends on off-chain indexing or data querying (for example, using The Graph to query historical events), you need to confirm whether indexing services are available on X Layer. The Graph documentation mentions that X Layer can be used as an indexing network, but you need to set the start block to the block where the contract was deployed to avoid scanning from the genesis block. If your original indexing solution does not support X Layer, this part needs to be reconfigured or replaced with another tool.

Also, X Layer launched Flashblocks in January 2026, reducing the chain-state finality of valid transactions from 1 second to 200 milliseconds. This is positive for user experience, but your frontend should not rely on the logic of "query status immediately after sending a transaction." 200 milliseconds is fast, but it is still not synchronous. After the transaction hash is returned, waiting for the receipt before updating the UI is the safer approach.

My Judgment: Get the Testnet Working First, Then Consider Mainnet

If you just want to extend an app already running on an EVM chain to X Layer, the contract-layer migration cost is very low. The frontend workload is mainly in wallet network configuration and address format handling. I suggest first going through the full flow of deployment, connection, read/write, and value transfer on the testnet (Chain ID 1952), confirming that every step has verifiable results, and then switching to mainnet. OKB on the testnet is free, but deployment and interaction on mainnet require real OKB. A single configuration error is a real cost.

If you don't have an OKX wallet or account yet, the invitation code field during registration is the referrer field. This site's promo code is 24U2795. It is optional and does not affect X Layer development and use.