Light Infra is a production API for gasless smart account transactions using ERC-4337. Send tokens, approve contracts, execute swaps, bridge cross-chain — all without users needing ETH for gas. The V2 API uses a prepare → sign → submit flow so private keys never leave the client.

Architecture

Supported Chains

Note: Lisk uses bridged versions of USDC and USDT — these are not native Circle/Tether tokens but ERC-20s bridged to Lisk via the canonical bridge. Same 6-decimal format.

LiskPaymaster Contract

A self-hosted verifying paymaster for Lisk (chain 1135), deployed because Pimlico does not support Lisk. ERC-4337 v0.7 paymaster spec with EntryPoint 0x0000000071727De22E5E9d8BAf0edAc6f37da032.

Supported Tokens

How It Works

Key Contract Functions

paymasterData Layout

The paymasterData field in the UserOperation is packed as:

Bundlers

Paymaster Routing

Gas Pricing (Lisk)

ETH price is fetched from the Enso API using Ethereum mainnet (chain ID 1) because Enso does not support the Lisk chain directly. We query the WETH price on mainnet — ETH price is the same regardless of chain:

GET https://api.enso.build/api/v1/prices/1/0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2
Authorization: Bearer ENSO_API_KEY

Token cost calculation (matches on-chain getTokenCostForGas):

// tokenCost = gasCostWei * ethPriceUsd * 10^decimals * markup / (1e18 * 10000)
const pricePerEth = ethPriceUsd * 10 ** tokenDecimals;  // e.g. 2500 * 1e6
const tokenCost = gasCostWei * pricePerEth * markup / (1e18 * 10000);

Gas fee estimation queries the Gelato bundler's minimum priority fee and the Lisk RPC gas price, takes the highest, then adds a 20% buffer:

// Lisk gas fees (never fails -- aggressive fallbacks)
maxPriorityFeePerGas = max(rpcGasPrice, bundlerMinPriority, 1_000_000) * 1.2
maxFeePerGas = rpcGasPrice * 3 + maxPriorityFeePerGas

V2 API — Client-Side Signing

The V2 endpoints use a prepare → sign → submit pattern. The server builds the UserOperation and returns a hash. The client signs it locally. The server relays it to the bundler.

Prepare UserOperation

{
  "ownerAddress": "0xYourEOAAddress",
  "chainId": 1135,
  "rpcUrl": "https://rpc.api.lisk.com",
  "tokenAddress": "0xF242275d3a6527d877f2c927a82D9b057609cc71",
  "recipient": "0xRecipientAddress",
  "amount": 5.0
}

{
  "ownerAddress": "0xYourEOAAddress",
  "chainId": 8453,
  "rpcUrl": "https://mainnet.base.org",
  "calls": [
    {
      "to": "0xRecipientAddress",
      "value": "1000000000000000000"
    }
  ],
  "paymasterToken": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"
}

{
  "success": true,
  "data": {
    "smartAccountAddress": "0xYourSafeAddress",
    "userOperation": {
      "sender": "0x...",
      "nonce": "0x...",
      "callData": "0x...",
      "callGasLimit": "0x...",
      "verificationGasLimit": "0x...",
      "preVerificationGas": "0x...",
      "maxFeePerGas": "0x...",
      "maxPriorityFeePerGas": "0x...",
      "paymaster": "0x...",
      "paymasterData": "0x...",
      "signature": "0x..."
    },
    "hashToSign": "0xabcdef...",
    "chainId": 1135
  },
  "message": "UserOperation prepared. Sign hashToSign with personal_sign..."
}

Submit Signed UserOperation

{
  "chainId": 1135,
  "userOperation": { /* full userOperation from /api/v2/prepare */ },
  "signature": "0x...your_personal_sign_result..."
}

{
  "success": true,
  "data": {
    "userOperationHash": "0x1234...",
    "chainId": 1135
  },
  "message": "UserOperation submitted successfully on chain 1135"
}

Cross-Chain Bridging (Across Protocol)

Bridge tokens between any supported chains using Across Protocol. The V2 bridge endpoint uses the same prepare → sign → submit flow — no private key needed. The server fetches an Across quote, builds the approve + depositV3 calls, and returns a UserOp for you to sign. Gas is paid in the token being bridged.

{
  "ownerAddress": "0xYourEOAAddress",
  "sourceChainId": 137,
  "destChainId": 42161,
  "rpcUrl": "https://polygon-rpc.com",
  "tokenAddress": "0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359",
  "amount": 50.0,
  "recipient": "0xRecipientOnDestChain"
}

{
  "success": true,
  "data": {
    "smartAccountAddress": "0x...",
    "userOperation": { /* ...full UserOp... */ },
    "hashToSign": "0xabcdef...",
    "chainId": 137,
    "bridge": {
      "sourceChainId": 137,
      "destChainId": 42161,
      "inputAmount": "50.0",
      "outputAmount": "49.85",
      "fee": "0.15",
      "estimatedFillTime": "~2-5 minutes"
    }
  },
  "message": "Sign hashToSign and submit to /api/v2/submit"
}

Wallet Integrations & Signing

The hashToSign from /api/v2/prepare is the Safe operation hash (EIP-712). Sign it with personal_sign using any wallet:

Privy

Privy embedded wallets work seamlessly. Use the useSignMessage hook:

Token Transfer

import { usePrivy, useSignMessage } from '@privy-io/react-auth';

function GaslessTransfer() {
  const { user } = usePrivy();
  const { signMessage } = useSignMessage();
  const address = user?.wallet?.address;

  async function send() {
    // Step 1: Prepare (send EOA address, NOT private key)
    const res = await fetch('/api/v2/prepare', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        ownerAddress: address,
        chainId: 137,
        rpcUrl: 'https://polygon-rpc.com',
        tokenAddress: '0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359',
        recipient: '0xRecipient',
        amount: 5.0,
      }),
    });
    const { data } = await res.json();

    // Step 2: Sign with Privy embedded wallet
    const signature = await signMessage(data.hashToSign);

    // Step 3: Submit
    await fetch('/api/v2/submit', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ chainId: 137, userOperation: data.userOperation, signature }),
    });
  }
}

ERC-20 Approve (any contract call)

import { usePrivy, useSignMessage } from '@privy-io/react-auth';

function GaslessApprove() {
  const { user } = usePrivy();
  const { signMessage } = useSignMessage();
  const address = user?.wallet?.address;

  async function approveToken(spender, amount) {
    // Use "calls" instead of tokenAddress/recipient/amount
    const res = await fetch('/api/v2/prepare', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        ownerAddress: address,
        chainId: 1135,
        rpcUrl: 'https://rpc.api.lisk.com',
        calls: [{
          to: '0xF242275d3a6527d877f2c927a82D9b057609cc71', // Bridged USDC on Lisk
          abi: ['function approve(address spender, uint256 amount)'],
          functionName: 'approve',
          args: [spender, amount],
        }],
        paymasterToken: '0xF242275d3a6527d877f2c927a82D9b057609cc71',
      }),
    });
    const { data } = await res.json();

    // Sign with Privy
    const signature = await signMessage(data.hashToSign);

    // Submit
    await fetch('/api/v2/submit', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ chainId: 1135, userOperation: data.userOperation, signature }),
    });
  }

  return (
    <button onClick={() => approveToken('0xDEXRouter', '1000000')}>
      Approve USDC
    </button>
  );
}

Cross-Chain Bridge

import { usePrivy, useSignMessage } from '@privy-io/react-auth';

function GaslessBridge() {
  const { user } = usePrivy();
  const { signMessage } = useSignMessage();
  const address = user?.wallet?.address;

  async function bridge() {
    // Step 1: Prepare bridge UserOp
    const res = await fetch('https://smart-wallet-519w.onrender.com/api/v2/bridge', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        ownerAddress: address,
        sourceChainId: 137,
        destChainId: 42161,
        rpcUrl: 'https://polygon-rpc.com',
        tokenAddress: '0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359',
        amount: 25.0,
      }),
    });
    const { data } = await res.json();

    // Step 2: Sign with Privy embedded wallet
    const signature = await signMessage(data.hashToSign);

    // Step 3: Submit
    await fetch('https://smart-wallet-519w.onrender.com/api/v2/submit', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ chainId: 137, userOperation: data.userOperation, signature }),
    });
  }
}

wagmi / RainbowKit / ConnectKit

Works with any wagmi-compatible wallet (MetaMask, WalletConnect, Coinbase Wallet, etc.):

import { useAccount, useSignMessage } from 'wagmi';
import { toBytes } from 'viem';

function GaslessAction() {
  const { address } = useAccount();
  const { signMessageAsync } = useSignMessage();

  async function execute() {
    // Prepare — works for transfers, approvals, any contract call
    const res = await fetch('/api/v2/prepare', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        ownerAddress: address,
        chainId: 8453,
        rpcUrl: 'https://mainnet.base.org',
        calls: [{ to: '0xContract', data: '0x...' }],
        paymasterToken: '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913',
      }),
    });
    const { data } = await res.json();

    // Sign with connected wallet (MetaMask, WalletConnect, etc.)
    const signature = await signMessageAsync({
      message: { raw: toBytes(data.hashToSign) },
    });

    // Submit
    await fetch('/api/v2/submit', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ chainId: 8453, userOperation: data.userOperation, signature }),
    });
  }
}

Cross-Chain Bridge

import { useAccount, useSignMessage } from 'wagmi';
import { toBytes } from 'viem';

function GaslessBridge() {
  const { address } = useAccount();
  const { signMessageAsync } = useSignMessage();

  async function bridge() {
    // Step 1: Prepare bridge UserOp
    const res = await fetch('https://smart-wallet-519w.onrender.com/api/v2/bridge', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        ownerAddress: address,
        sourceChainId: 8453,
        destChainId: 42161,
        rpcUrl: 'https://mainnet.base.org',
        tokenAddress: '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913',
        amount: 100.0,
      }),
    });
    const { data } = await res.json();

    // Step 2: Sign with connected wallet (MetaMask, WalletConnect, etc.)
    const signature = await signMessageAsync({
      message: { raw: toBytes(data.hashToSign) },
    });

    // Step 3: Submit
    await fetch('https://smart-wallet-519w.onrender.com/api/v2/submit', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ chainId: 8453, userOperation: data.userOperation, signature }),
    });
  }
}

Server-Side Signing (ethers.js)

For backend services, bots, or automation — generate or use a private key server-side:

import { ethers } from 'ethers';

// Generate a new wallet (or use existing key)
const wallet = ethers.Wallet.createRandom();
// Or: const wallet = new ethers.Wallet('0xYourPrivateKey');

console.log('EOA:', wallet.address);  // save this
console.log('Key:', wallet.privateKey); // store securely!

// Prepare any transaction
const prepareRes = await fetch('https://smart-wallet-519w.onrender.com/api/v2/prepare', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    ownerAddress: wallet.address,
    chainId: 1135,
    rpcUrl: 'https://rpc.api.lisk.com',
    tokenAddress: '0xF242275d3a6527d877f2c927a82D9b057609cc71',
    recipient: '0xRecipient',
    amount: 10.0,
  }),
});
const { data } = await prepareRes.json();

// Sign locally
const signature = await wallet.signMessage(ethers.utils.arrayify(data.hashToSign));

// Submit
const result = await fetch('https://smart-wallet-519w.onrender.com/api/v2/submit', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({ chainId: 1135, userOperation: data.userOperation, signature }),
}).then(r => r.json());

console.log('UserOp:', result.data.userOperationHash);

Cross-Chain Bridge

import { ethers } from 'ethers';

const wallet = new ethers.Wallet('0xYourPrivateKey');

// Step 1: Prepare bridge UserOp
const prepareRes = await fetch('https://smart-wallet-519w.onrender.com/api/v2/bridge', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    ownerAddress: wallet.address,
    sourceChainId: 137,
    destChainId: 42161,
    rpcUrl: 'https://polygon-rpc.com',
    tokenAddress: '0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359',
    amount: 50.0,
  }),
});
const { data: bridgeData } = await prepareRes.json();

// Step 2: Sign locally with ethers.Wallet.signMessage
const bridgeSig = await wallet.signMessage(ethers.utils.arrayify(bridgeData.hashToSign));

// Step 3: Submit
const bridgeResult = await fetch('https://smart-wallet-519w.onrender.com/api/v2/submit', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({ chainId: 137, userOperation: bridgeData.userOperation, signature: bridgeSig }),
}).then(r => r.json());

console.log('Bridge UserOp:', bridgeResult.data.userOperationHash);

MetaMask / Browser window.ethereum

const signature = await window.ethereum.request({
  method: 'personal_sign',
  params: [hashToSign, ownerAddress],
});

viem (standalone)

import { privateKeyToAccount } from 'viem/accounts';
const account = privateKeyToAccount(privateKey);
const signature = await account.signMessage({ message: { raw: hashToSign } });

Examples

Token Transfer

curl -X POST https://smart-wallet-519w.onrender.com/api/v2/prepare \
  -H "Content-Type: application/json" \
  -d '{
    "ownerAddress": "0xYourEOA",
    "chainId": 1135,
    "rpcUrl": "https://rpc.api.lisk.com",
    "tokenAddress": "0xF242275d3a6527d877f2c927a82D9b057609cc71",
    "recipient": "0xRecipient",
    "amount": 5.0
  }'

ERC-20 Approve (any chain including Lisk)

Approve a contract to spend tokens on your behalf. Works on all chains:

curl -X POST https://smart-wallet-519w.onrender.com/api/v2/prepare \
  -H "Content-Type: application/json" \
  -d '{
    "ownerAddress": "0xYourEOA",
    "chainId": 1135,
    "rpcUrl": "https://rpc.api.lisk.com",
    "calls": [
      {
        "to": "0xF242275d3a6527d877f2c927a82D9b057609cc71",
        "abi": ["function approve(address spender, uint256 amount)"],
        "functionName": "approve",
        "args": ["0xSpenderContract", "1000000000"]
      }
    ],
    "paymasterToken": "0xF242275d3a6527d877f2c927a82D9b057609cc71"
  }'

Multi-Call: Approve + Swap (single UserOp)

Execute multiple contract calls atomically in one transaction:

curl -X POST https://smart-wallet-519w.onrender.com/api/v2/prepare \
  -H "Content-Type: application/json" \
  -d '{
    "ownerAddress": "0xYourEOA",
    "chainId": 8453,
    "rpcUrl": "https://mainnet.base.org",
    "calls": [
      {
        "to": "0xTokenAddress",
        "abi": ["function approve(address,uint256)"],
        "functionName": "approve",
        "args": ["0xDEXRouter", "1000000"]
      },
      {
        "to": "0xDEXRouter",
        "data": "0x...encoded swap calldata..."
      }
    ],
    "paymasterToken": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"
  }'

Raw Calldata (any contract interaction)

curl -X POST https://smart-wallet-519w.onrender.com/api/v2/prepare \
  -H "Content-Type: application/json" \
  -d '{
    "ownerAddress": "0xYourEOA",
    "chainId": 1135,
    "rpcUrl": "https://rpc.api.lisk.com",
    "calls": [
      {
        "to": "0xAnyContract",
        "data": "0xabcdef...raw calldata...",
        "value": "0"
      }
    ],
    "paymasterToken": "0xF242275d3a6527d877f2c927a82D9b057609cc71"
  }'

Cross-Chain Bridge (Across Protocol)

Bridge USDC from Polygon to Arbitrum (client-side signing):

# Step 1: Prepare bridge UserOp
curl -X POST https://smart-wallet-519w.onrender.com/api/v2/bridge \
  -H "Content-Type: application/json" \
  -d '{
    "ownerAddress": "0xYourEOA",
    "sourceChainId": 137,
    "destChainId": 42161,
    "rpcUrl": "https://polygon-rpc.com",
    "tokenAddress": "0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359",
    "amount": 50.0
  }'

# Step 2: Sign hashToSign locally with your wallet

# Step 3: Submit signed UserOp
curl -X POST https://smart-wallet-519w.onrender.com/api/v2/submit \
  -H "Content-Type: application/json" \
  -d '{
    "chainId": 137,
    "userOperation": { "...from prepare response..." },
    "signature": "0x...your signature..."
  }'

Use with Claude / LLMs

You can give Claude (or any LLM) the API reference file so it can build transactions for you. Download the markdown file and include it in your prompt context:

Download api-reference.md

How to use with Claude

# In your Claude prompt / system prompt, include:

You have access to the Light Infra API. Here is the API reference:

<api-reference>
{paste contents of api-reference.md}
</api-reference>

Use the /api/v2/prepare and /api/v2/submit endpoints to build
gasless transactions. The user will sign the hashToSign locally.

Example Claude interaction

User: Send 10 USDC to 0xBob on Polygon, my address is 0xAlice

Claude: I'll prepare a gasless USDC transfer for you.

curl -X POST https://smart-wallet-519w.onrender.com/api/v2/prepare \
  -H "Content-Type: application/json" \
  -d '{
    "ownerAddress": "0xAlice",
    "chainId": 137,
    "rpcUrl": "https://polygon-rpc.com",
    "tokenAddress": "0x3c499c542cEF5E3811e1192ce70d8cC03d5c3359",
    "recipient": "0xBob",
    "amount": 10.0
  }'

Sign the hashToSign from the response, then submit:

curl -X POST https://smart-wallet-519w.onrender.com/api/v2/submit ...