JSON-RPC APIs¶

Introduction¶

Asset Hub provides Ethereum compatibility through its JSON-RPC interface, allowing developers to interact with the chain using familiar Ethereum tooling and methods. This document outlines the supported Ethereum JSON-RPC methods and provides examples of how to use them.

This article uses the Westend Asset Hub endpoint to interact with:

https://westend-asset-hub-eth-rpc.polkadot.io

Available Methods¶

eth_accounts¶

Returns a list of addresses owned by the client. Reference.

Parameters:

None

Example:

eth_accounts

curl -X POST https://westend-asset-hub-rpc.polkadot.io \
-H "Content-Type: application/json" \
--data '{
    "jsonrpc":"2.0",
    "method":"eth_accounts",
    "params":[],
    "id":1
}'

eth_blockNumber¶

Returns the number of the most recent block. Reference.

Parameters:

None

Example:

eth_blockNumber

curl -X POST https://westend-asset-hub-rpc.polkadot.io \
-H "Content-Type: application/json" \
--data '{
    "jsonrpc":"2.0",
    "method":"eth_blockNumber",
    "params":[],
    "id":1
}'

eth_call¶

Executes a new message call immediately without creating a transaction. Reference.

Parameters:

transaction object - the transaction call object:
- to string - recipient address of the call. Must be a 20-byte data string
- data string - hash of the method signature and encoded parameters. Must be a data string
- from string - (optional) sender's address for the call. Must be a 20-byte data string
- gas string - (optional) gas limit to execute the call. Must be a quantity string
- gasPrice string - (optional) gas price per unit of gas. Must be a quantity string
- value string - (optional) value in wei to send with the call. Must be a quantity string
blockValue string - (optional) block tag or block number to execute the call at. Must be a quantity string or a default block parameter

Example:

eth_call

curl -X POST https://westend-asset-hub-rpc.polkadot.io \
-H "Content-Type: application/json" \
--data '{
    "jsonrpc":"2.0",
    "method":"eth_call",
    "params":[{
        "to": "INSERT_RECIPIENT_ADDRESS",
        "data": "INSERT_ENCODED_CALL"
    }, "INSERT_BLOCK_VALUE"],
    "id":1
}'

Ensure to replace the INSERT_RECIPIENT_ADDRESS, INSERT_ENCODED_CALL, and INSERT_BLOCK_VALUE with the proper values.

eth_chainId¶

Returns the chain ID used for signing transactions. Reference.

Parameters:

None

Example:

eth_chainId

curl -X POST https://westend-asset-hub-rpc.polkadot.io \
-H "Content-Type: application/json" \
--data '{
    "jsonrpc":"2.0",
    "method":"eth_chainId",
    "params":[],
    "id":1
}'

eth_estimateGas¶

Estimates gas required for a transaction. Reference.

Parameters:

transaction object - the transaction call object:
- to string - recipient address of the call. Must be a 20-byte data string
- data string - hash of the method signature and encoded parameters. Must be a data string
- from string - (optional) sender's address for the call. Must be a 20-byte data string
- gas string - (optional) gas limit to execute the call. Must be a quantity string
- gasPrice string - (optional) gas price per unit of gas. Must be a quantity string
- value string - (optional) value in wei to send with the call. Must be a quantity string
blockValue string - (optional) block tag or block number to execute the call at. Must be a quantity string or a default block parameter

Example:

eth_estimateGas

curl -X POST https://westend-asset-hub-eth-rpc.polkadot.io \
-H "Content-Type: application/json" \
--data '{
    "jsonrpc":"2.0",
    "method":"eth_estimateGas",
    "params":[{
        "to": "INSERT_RECIPIENT_ADDRESS",
        "data": "INSERT_ENCODED_FUNCTION_CALL"
    }],
    "id":1
}'

Ensure to replace the INSERT_RECIPIENT_ADDRESS and INSERT_ENCODED_CALL with the proper values.

eth_gasPrice¶

Returns the current gas price in Wei. Reference.

Parameters:

None

Example:

eth_gasPrice

curl -X POST https://westend-asset-hub-eth-rpc.polkadot.io \
-H "Content-Type: application/json" \
--data '{
    "jsonrpc":"2.0",
    "method":"eth_gasPrice",
    "params":[],
    "id":1
}'

eth_getBalance¶

Returns the balance of a given address. Reference.

Parameters:

address string - address to query balance. Must be a 20-byte data string
blockValue string - (optional) the block value to be fetched. Must be a quantity string or a default block parameter

Example:

eth_getBalance

curl -X POST https://westend-asset-hub-rpc.polkadot.io \
-H "Content-Type: application/json" \
--data '{
    "jsonrpc":"2.0",
    "method":"eth_getBalance",
    "params":["INSERT_ADDRESS", "INSERT_BLOCK_VALUE"],
    "id":1
}'

Ensure to replace the INSERT_ADDRESS and INSERT_BLOCK_VALUE with the proper values.

eth_getBlockByHash¶

Returns information about a block by its hash. Reference.

Parameters:

blockHash string – the hash of the block to retrieve. Must be a 32 byte data string
fullTransactions boolean – if true, returns full transaction details; if false, returns only transaction hashes

Example:

eth_getBlockByHash

curl -X POST https://westend-asset-hub-rpc.polkadot.io \
-H "Content-Type: application/json" \
--data '{
    "jsonrpc":"2.0",
    "method":"eth_getBlockByHash",
    "params":["INSERT_BLOCK_HASH", INSERT_BOOLEAN],
    "id":1
}'

Ensure to replace the INSERT_BLOCK_HASH and INSERT_BOOLEAN with the proper values.

eth_getBlockByNumber¶

Returns information about a block by its number. Reference.

Parameters:

blockValue string - (optional) the block value to be fetched. Must be a quantity string or a default block parameter
fullTransactions boolean – if true, returns full transaction details; if false, returns only transaction hashes

Example:

eth_getBlockByNumber

curl -X POST https://westend-asset-hub-rpc.polkadot.io \
-H "Content-Type: application/json" \
--data '{
    "jsonrpc":"2.0",
    "method":"eth_getBlockByNumber",
    "params":["INSERT_BLOCK_VALUE", INSERT_BOOLEAN],
    "id":1
}'

Ensure to replace the INSERT_BLOCK_VALUE and INSERT_BOOLEAN with the proper values.

eth_getCode¶

Returns the code at a given address. Reference.

Parameters:

address string - contract or account address to query code. Must be a 20-byte data string
blockValue string - (optional) the block value to be fetched. Must be a quantity string or a default block parameter

Example:

eth_getCode

curl -X POST https://westend-asset-hub-eth-rpc.polkadot.io \
-H "Content-Type: application/json" \
--data '{
    "jsonrpc":"2.0",
    "method":"eth_getCode",
    "params":["INSERT_ADDRESS", "INSERT_BLOCK_VALUE"],
    "id":1
}'

Ensure to replace the INSERT_ADDRESS and INSERT_BLOCK_VALUE with the proper values.

eth_getStorageAt¶

Returns the value from a storage position at a given address. Reference.

Parameters:

address string - contract or account address to query code. Must be a 20-byte data string
storageKey string - position in storage to retrieve data from. Must be a quantity string
blockValue string - (optional) the block value to be fetched. Must be a quantity string or a default block parameter

Example:

eth_getStorageAt

curl -X POST https://westend-asset-hub-eth-rpc.polkadot.io \
-H "Content-Type: application/json" \
--data '{
    "jsonrpc":"2.0",
    "method":"eth_getStorageAt",
    "params":["INSERT_ADDRESS", "INSERT_STORAGE_KEY", "INSERT_BLOCK_VALUE"],
    "id":1
}'

Ensure to replace the INSERT_ADDRESS, INSERT_STORAGE_KEY, and INSERT_BLOCK_VALUE with the proper values.

eth_getTransactionCount¶

Returns the number of transactions sent from an address (nonce). Reference.

Parameters:

address string - address to query balance. Must be a 20-byte data string
blockValue string - (optional) the block value to be fetched. Must be a quantity string or a default block parameter

Example:

eth_getTransactionCount

curl -X POST https://westend-asset-hub-rpc.polkadot.io \
-H "Content-Type: application/json" \
--data '{
    "jsonrpc":"2.0",
    "method":"eth_getTransactionCount",
    "params":["INSERT_ADDRESS", "INSERT_BLOCK_VALUE"],
    "id":1
}'

Ensure to replace the INSERT_ADDRESS and INSERT_BLOCK_VALUE with the proper values.

eth_maxPriorityFeePerGas¶

Returns an estimate of the current priority fee per gas, in Wei, to be included in a block.

Parameters:

None

Example:

eth_maxPriorityFeePerGas

curl -X POST https://westend-asset-hub-eth-rpc.polkadot.io \
-H "Content-Type: application/json" \
--data '{
    "jsonrpc":"2.0",
    "method":"eth_maxPriorityFeePerGas",
    "params":[],
    "id":1
}'

eth_sendRawTransaction¶

Submits a raw transaction. Reference.

Parameters:

callData string - signed transaction data. Must be a data string

Example:

eth_sendRawTransaction

curl -X POST https://westend-asset-hub-rpc.polkadot.io \
-H "Content-Type: application/json" \
--data '{
    "jsonrpc":"2.0",
    "method":"eth_sendRawTransaction",
    "params":["INSERT_CALL_DATA"],
    "id":1
}'

Ensure to replace the INSERT_CALL_DATA with the proper values.

eth_sendTransaction¶

Creates and sends a new transaction. Reference.

Parameters:

transaction object - the transaction object:
- from string - address sending the transaction. Must be a 20-byte data string
- to string - (optional) recipient address. No need to provide this value when deploying a contract. Must be a 20-byte data string
- gas string - (optional, default: 90000) gas limit for execution. Must be a quantity string
- gasPrice string - (optional) gas price per unit. Must be a quantity string
- value string - (optional) amount of Ether to send. Must be a quantity string
- data string - (optional) contract bytecode or encoded method call. Must be a data string
- nonce string - (optional) transaction nonce. Must be a quantity string

Example:

eth_sendTransaction

curl -X POST https://westend-asset-hub-rpc.polkadot.io \
-H "Content-Type: application/json" \
--data '{
    "jsonrpc":"2.0",
    "method":"eth_sendTransaction",
    "params":[{
        "from": "INSERT_SENDER_ADDRESS",
        "to": "INSERT_RECIPIENT_ADDRESS",
        "gas": "INSERT_GAS_LIMIT",
        "gasPrice": "INSERT_GAS_PRICE",
        "value": "INSERT_VALUE",
        "input": "INSERT_INPUT_DATA",
        "nonce": "INSERT_NONCE"
    }],
    "id":1
}'

Ensure to replace the INSERT_SENDER_ADDRESS, INSERT_RECIPIENT_ADDRESS, INSERT_GAS_LIMIT, INSERT_GAS_PRICE, INSERT_VALUE, INSERT_INPUT_DATA, and INSERT_NONCE with the proper values.

net_version¶

Returns the current network ID as a string. Reference.

Parameters:

None

Example:

net_version

curl -X POST https://westend-asset-hub-rpc.polkadot.io \
-H "Content-Type: application/json" \
--data '{
    "jsonrpc":"2.0",
    "method":"net_version",
    "params":[],
    "id":1
}'

Response Format¶

All responses follow the standard JSON-RPC 2.0 format:

{
    "jsonrpc": "2.0",
    "id": 1,
    "result": ... // The return value varies by method
}

Error Handling¶

If an error occurs, the response will include an error object:

{
    "jsonrpc": "2.0",
    "id": 1,
    "error": {
        "code": -32000,
        "message": "Error message here"
    }
}

Last update: March 6, 2025
| Created: March 6, 2025