Web3 It’s a high level, user-friendly and support middleware Ethereum JSON-RPC Client.

Features

• Ethereum JSON-RPC Client
• Interacting smart contracts
• Querying past events
• Event monitoring as Streams
• Websockets

Example 1

# Defining the application
defmodule MyApp.Application do
  use Web3, rpc_endpoint: "<PATH_TO_RPC_ENDPOINT>"

  # middleware (optional)
  middleware MyApp.Middleware.Logger

  # dispatch (optional)
  dispatch :eth_getBalance, args: 2

  # contract (optinnal)
  contract :FirstContract, contract_address: "0xdAC17F958D2ee523a2206206994597C13D831ec7", abi_path: "path_to_abi.json"
end

# (Optional) If you need to customise your middleware.
defmodule MyApp.Middleware.Logger do
  @moduledoc false

  @behaviour Web3.Middleware

  require Logger
  alias Web3.Middleware.Pipeline
  import Pipeline

  @doc "Before Request HTTP JSON RPC"
  def before_dispatch(%Pipeline{} = pipeline) do
    # Set metadata assigns here.
    Logger.info("MyApp before_dispatch")
    pipeline
  end

  @doc "After Request HTTP JSON RPC"
  def after_dispatch(%Pipeline{} = pipeline) do
    Logger.info("MyApp after_dispatch")
    pipeline
  end

  @doc "When after request HTTP JSON RPC failed"
  def after_failure(%Pipeline{} = pipeline) do
    Logger.info("MyApp after_failure")
    pipeline
  end
end

# Get latest block number
iex> MyApp.Application.eth_blockNumber
{:ok, 15034908}

# Get address balance.
iex> MyApp.Application.eth_getBalance("0xF4986360a6d873ea02F79eC3913be6845e0308A4", "latest")
{:ok, 0}

# Get multi-addresses balance.
iex> MyApp.Application.eth_getBalance(["0xF4986360a6d873ea02F79eC3913be6845e0308A4", "0xF4986360a6d873ea02F79eC3913be6845e0308A4"], "latest")
{:ok,
  %{
    errors: [],
    params: ["0xF4986360a6d873ea02F79eC3913be6845e0308A4", "0xF4986360a6d873ea02F79eC3913be6845e0308A4"],
    result: [0, 0]
  }
}

# Query Contract
iex> MyApp.Application.FirstContract.balanceOf_address_("0xF4986360a6d873ea02F79eC3913be6845e0308A4")
{:ok, 0}

# Make Transaction
iex> MyApp.Application.FirstContract.approve_address_uint256_(
  "0x0000000000000000000000000000000000000000",
  10,
  gas_price: 12_000_000_000,
  gas_limit: 300_000,
  chain_id: 1,
  nonce: 1,
  priv_key: "xxxxxxxxxxxxxxxxxxxxxxxxx"
)

{:ok, true}

More information on web3.

Thank you for reading, have a good day.