Getting Started

Installation

npm i @3loop/transaction-decoder viem effect

Quick Start

Loop Decoder requires three components:

1. RPC Provider
2. ABI Data Store
3. Contract Metadata Store

This guide demonstrates setup using the default in-memory implementations for Data Stores (see and run Full Example Code from this page). For custom storage solutions, see our How To Decode Transaction guide.

1. Set up your RPC Provider

Create a getPublicClient function that accepts a chain ID and returns an object with Viem PublicClient.

provider.ts

import { createPublicClient, http } from 'viem'

// Create a public client for the Ethereum Mainnet network
const getPublicClient = (chainId: number) => {
  return {
    client: createPublicClient({
      transport: http('https://rpc.ankr.com/eth'),
    }),
  }
}

For detailed configuration options and trace API settings, see the RPC Provider documentation.

2. Initialize ABI Data Store

The InMemoryAbiStoreLive provides default ABI loading and caching functionality:

• Fetches ABIs from multiple sources (Etherscan, 4bytes, Openchain, Sourcify)
• Caches results in memory

import { InMemoryAbiStoreLive } from '@3loop/transaction-decoder/in-memory'
import { EtherscanV2StrategyResolver } from '@3loop/transaction-decoder'

const abiStore = InMemoryAbiStoreLive.make({
  default: [
    EtherscanV2StrategyResolver({
      apikey: 'YourApiKey', // provide Etherscan V2 API key
    }),
  ],
})

For a custom implementation, see our How To Decode Transaction (ABI Data Store) guide.

3. Initialize Contract Metadata Store

The InMemoryContractMetaStoreLive handles contract metadata resolution:

• Resolves ERC20, ERC721 and ERC1155 metadata using RPC calls
• Caches results in memory

import { ERC20RPCStrategyResolver, ProxyRPCStrategyResolver, PublicClient } from '@3loop/transaction-decoder'
import { InMemoryContractMetaStoreLive } from '@3loop/transaction-decoder/in-memory'
import { Effect, Layer } from 'effect'

const contractMetaStore = Layer.unwrapEffect(
  Effect.gen(function* () {
    const service = yield* PublicClient

    return InMemoryContractMetaStoreLive.make({
      default: [ERC20RPCStrategyResolver(service), ProxyRPCStrategyResolver(service)],
    })
  }),
)

For a custom implementation, see our How To Decode Transaction (Contract Metadata Store) guide.

4. Decode a Transaction

Finally, you can create a new instance of the LoopDecoder class and invoke decodeTransaction method with the transaction hash and chain ID:

import { TransactionDecoder } from '@3loop/transaction-decoder'

const decoder = new TransactionDecoder({
  getPublicClient: getPublicClient,
  abiStore,
  contractMetaStore,
})

const decoded = await decoder.decodeTransaction({
  chainID: 1,
  hash: '0x...',
})

Live Demo