# JSON RPC API

# The Ethereum RPC API

MetaMask uses the ethereum.sendAsync() API to wrap an RPC API which is based on an interface exposed by all Ethereum clients, with some extra methods that are provided by MetaMask, as a key-holding signer.

This document is a cross-post of EIP 1474, which aims to standardize the declaration of this interface.

eip: 1474
title: Remote procedure call specification
author: Paul Bouchon <mail@bitpshr.net>
discussions-to: https://ethereum-magicians.org/t/eip-remote-procedure-call-specification/1537
status: Draft
type: Standards Track
category: Interface
created: 2018-10-02

# Simple Summary

This proposal defines a standard set of remote procedure call methods that an Ethereum node should implement.

# Abstract

Nodes created by the current generation of Ethereum clients expose inconsistent and incompatible remote procedure call (RPC) methods because no formal Ethereum RPC specification exists. This proposal standardizes such a specification to provide developers with a predictable Ethereum RPC interface regardless of underlying node implementation.

# Specification

# Concepts

# RFC-2119

The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be interpreted as described in RFC-2119.

# JSON-RPC

Communication with Ethereum nodes is accomplished using JSON-RPC, a stateless, lightweight remote procedure call protocol that uses JSON as its data format. Ethereum RPC methods MUST be called using JSON-RPC request objects and MUST respond with JSON-RPC response objects.

# Error codes

If an Ethereum RPC method encounters an error, the error member included on the response object MUST be an object containing a code member and descriptive message member. The following list contains all possible error codes and associated messages:

Example error response:

{
    "id": 1337
    "jsonrpc": "2.0",
    "error": {
        "code": -32003,
        "message": "Transaction rejected"
    }
}

# Value encoding

Specific types of values passed to and returned from Ethereum RPC methods require special encoding:

# Quantity

• A Quantity value MUST be hex-encoded.
• A Quantity value MUST be “0x”-prefixed.
• A Quantity value MUST be expressed using the fewest possible hex digits per byte.
• A Quantity value MUST express zero as “0x0”.

Examples Quantity values:

# Data

• A Data value MUST be hex-encoded.
• A Data value MUST be “0x”-prefixed.
• A Data value MUST be expressed using two hex digits per byte.

Examples Data values:

# Proposing changes

New Ethereum RPC methods and changes to existing methods MUST be proposed via the traditional EIP process. This allows for community consensus around new method implementations and proposed method modifications. RPC method proposals MUST reach “draft” status before being added to this proposal and the official Ethereum RPC specification defined herein.

# Methods

# web3_clientVersion

# web3_sha3

# net_listening

# net_peerCount

# net_version

# eth_accounts

# eth_blockNumber

# eth_call

# eth_coinbase

# eth_estimateGas

# eth_gasPrice

# eth_getBalance

# eth_getBlockByHash

# eth_getBlockByNumber

# eth_getBlockTransactionCountByHash

# eth_getBlockTransactionCountByNumber

# eth_getCode

# eth_getFilterChanges

# eth_getFilterLogs

# eth_getLogs

# eth_getStorageAt

# eth_getTransactionByBlockHashAndIndex

# eth_getTransactionByBlockNumberAndIndex

# eth_getTransactionByHash

# eth_getTransactionCount

# eth_getTransactionReceipt

# eth_getUncleByBlockHashAndIndex

# eth_getUncleByBlockNumberAndIndex

# eth_getUncleCountByBlockHash

# eth_getUncleCountByBlockNumber

# eth_getWork

# eth_hashrate

# eth_mining

# eth_newBlockFilter

# eth_newFilter

# eth_newPendingTransactionFilter

# eth_protocolVersion

# eth_sendRawTransaction

# eth_sendTransaction

# eth_sign

# eth_signTransaction

# eth_signTypedData

# eth_submitHashrate

# eth_submitWork

# eth_syncing

# eth_uninstallFilter