3. Supported Tokens

Developers should query the current list of supported tokens before attempting gasless transactions.

3.1. Token Eligibility Criteria

• ERC-20 Compliance: Tokens must be fully ERC-20 compliant.
• No Fee-on-Transfer: Fee-on-Transfer (FoT) tokens are not supported, as they can cause swap amounts to mismatch, leading to transaction failure.
• Governance Whitelist: The GaslessSwapRouter maintains a list of supported tokens, which is managed by Kaia Foundation.

3.2 Currently Supported Tokens

Gasless transactions currently support the following tokens. Additional CL tokens and stablecoins may be included in the future.

• USDT
• BORA

3.3 How to Check the Supported Token List

You can find the official KIP-247 GaslessSwapRouter contract addresses for both mainnet and testnet in the Kaia Docs.

GaslessSwapRouter Contract Addresses:

• Mainnet: 0xCf658F786bf4AC62D66d70Dd26B5c1395dA22c63
• Kairos Testnet: 0x4b41783732810b731569E4d944F59372F411BEa2

Always refer to the official documentation for the most current address.

Using Block Explorer (KaiaScan)

To check the supported tokens using a block explorer like KaiaScan:

1. Go to KaiaScan (or kairos.kaiascan.io for the testnet).
2. Search for the GaslessSwapRouter address.
3. Navigate to the Contract tab and select Read Contract.
4. Find the getSupportedTokens() function and click Query. This will return an array of supported ERC20 token addresses.

Programmatic Query

To programmatically check supported tokens, you can use the GaslessSwapRouter contract methods.

Use GSR methods:

function getSupportedTokens() external view returns (address[] memory);

function dexAddress(address token) external view returns (address dex); // reverts if token unsupported

Use SDK (Example)

// Ethers-ext.js

const ethers = require("ethers6");

const { gasless } = require('@kaiachain/ethers-ext');

const provider = new ethers.JsonRpcProvider(RPC_URL);

const router = await gasless.getGaslessSwapRouter(provider);

const supported = await router.getSupportedTokens();

// Web3-ext.js

const { Web3 } = require("@kaiachain/web3js-ext");

const provider = new Web3.providers.HttpProvider(RPC_URL);

const web3 = new Web3(provider);

const router = await gasless.getGaslessSwapRouter(web3);

const supported = await router.methods.getSupportedTokens().call();