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contract-chain-c-chain-api.md

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description The C-Chain is an instance of the Ethereum Virtual Machine (EVM)

Contract Chain (C-Chain) API

Note: Ethereum has its own notion of networkID and chainID. These have no relationship to Avalanche’s view of networkID and chainID and are purely internal to the C-Chain. On Mainnet, the C-Chain uses 1 and 43114 for these values. On the Fuji Testnet, it uses 1 and 43113 for these values. networkID and chainID can also be obtained using the net_version and eth_chainId methods.

Deploying a Smart Contract

{% page-ref page="../tutorials/smart-contracts/deploy-a-smart-contract-on-avalanche-using-remix-and-metamask.md" %}

Ethereum APIs

Ethereum API Endpoints

JSON-RPC Endpoints

To interact with C-Chain via the JSON-RPC endpoint:

/ext/bc/C/rpc

To interact with other instances of the EVM via the JSON-RPC endpoint:

/ext/bc/blockchainID/rpc

where blockchainID is the ID of the blockchain running the EVM.

WebSocket Endpoints

To interact with C-Chain via the websocket endpoint:

/ext/bc/C/ws

For example, to interact with the C-Chain's Ethereum APIs via websocket on localhost you can use:

ws://127.0.0.1:9650/ext/bc/C/ws

To interact with other instances of the EVM via the websocket endpoint:

/ext/bc/blockchainID/ws

where blockchainID is the ID of the blockchain running the EVM.

Methods

Standard Ethereum APIs

Avalanche offers an API interface identical to Geth's API except that it only supports the following services:

  • web3_
  • net_
  • eth_
  • personal_
  • txpool_
  • debug_

You can interact with these services the same exact way you’d interact with Geth. See the Ethereum Wiki’s JSON-RPC Documentation and Geth’s JSON-RPC Documentation for a full description of this API.

eth_getAssetBalance

In addition to the standard Ethereum APIs, Avalanche offers eth_getAssetBalance to retrieve the balance of first class Avalanche Native Tokens on the C-Chain (excluding AVAX, which must be fetched with eth_getBalance).

Signature

eth_getAssetBalance({
    address: string,
    blk: BlkNrOrHash,
    assetID: string,
}) -> {balance: int}
  • address owner of the asset
  • blk is the block number or hash at which to retrieve the balance
  • assetID id of the asset for which the balance is requested

Example Call

curl -X POST --data '{
    "jsonrpc": "2.0",
    "method": "eth_getAssetBalance",
    "params": [
        "0x8723e5773847A4Eb5FeEDabD9320802c5c812F46",
        "latest",
        "3RvKBAmQnfYionFXMfW5P8TDZgZiogKbHjM8cjpu16LKAgF5T"
    ],
    "id": 1
}' -H 'content-type:application/json;' 127.0.0.1:9650/ext/bc/C/rpc

Example Response

{
    "jsonrpc": "2.0",
    "id": 1,
    "result": "0x1388"
}

Avalanche Specific APIs

Avalanche Specific API Endpoints

To interact with the avax specific RPC calls on the C-Chain:

/ext/bc/C/avax

To interact with other instances of the EVM AVAX endpoints:

/ext/bc/blockchainID/avax

avax.export

Export an asset from the C-Chain to the X-Chain. After calling this method, you must call avm.import on the X-Chain to complete the transfer.

Signature

avax.export({
    to: string,
    amount: int,
    assetID: string,
    username: string,
    password:string,
}) -> {txID: string}
  • to is the X-Chain address the asset is sent to.
  • amount is the amount of the asset to send.
  • assetID is the ID of the asset. To export AVAX use "AVAX" as the assetID.
  • The asset is sent from addresses controlled by username and password.

Example Call

curl -X POST --data '{
    "jsonrpc":"2.0",
    "id"     :1,
    "method" :"avax.export",
    "params" :{
        "to":"X-avax1q9c6ltuxpsqz7ul8j0h0d0ha439qt70sr3x2m0",
        "amount": 500,
        "assetID": "2nzgmhZLuVq8jc7NNu2eahkKwoJcbFWXWJCxHBVWAJEZkhquoK",
        "username":"myUsername",
        "password":"myPassword"
    }
}' -H 'content-type:application/json;' 127.0.0.1:9650/ext/bc/C/avax

Example Response

{
    "jsonrpc": "2.0",
    "result": {
        "txID": "2W5JuFENitZKTpJsy9igBpTcEeBKxBHHGAUkgsSUnkjVVGQ9i8"
    },
    "id": 1
}

avax.exportAVAX

DEPRECATED—instead use avax.export.

Send AVAX from the C-Chain to the X-Chain. After calling this method, you must call avm.importAVAX on the X-Chain to complete the transfer.

Signature

avax.exportAVAX({
    to: string,
    amount: int,
    destinationChain: string,
    from: []string, //optional
    changeAddr: string, //optional
    username: string,
    password:string,
}) -> {txID: string}

Request

  • from is the C-Chain addresses the AVAX is sent from. They should be in hex format.
  • to is the X-Chain address the AVAX is sent to. It should be in bech32 format.
  • amount is the amount of nAVAX to send.
  • destinationChain is the chain the AVAX is sent to. To export funds to the X-Chain, use "X".
  • changeAddr is the C-Chain address where any change is sent to. It should be in hex format.
  • The AVAX is sent from addresses controlled by username

Response

  • txID is the txid of the completed ExportTx.

Example Call

curl -X POST --data '{
    "jsonrpc":"2.0",
    "id"     :1,
    "method" :"avax.exportAVAX",
    "params" :{
        "from": ["0x8db97C7cEcE249c2b98bDC0226Cc4C2A57BF52FC"],
        "to":"X-avax1q9c6ltuxpsqz7ul8j0h0d0ha439qt70sr3x2m0",
        "amount": 500,
        "destinationChain": "X",
        "changeAddr": "0x8db97C7cEcE249c2b98bDC0226Cc4C2A57BF52FC",
        "username":"myUsername",
        "password":"myPassword"
    }
}' -H 'content-type:application/json;' 127.0.0.1:9650/ext/bc/C/avax

Example Response

{
    "jsonrpc": "2.0",
    "result": {
        "txID": "2ffcxdkiKXXA4JdyRoS38dd7zoThkapNPeZuGPmmLBbiuBBHDa"
    },
    "id": 1
}

avax.exportKey

Get the private key that controls a given address. The returned private key can be added to a user with avax.importKey.

Signature

avax.exportKey({
    username: string,
    password:string,
    address:string
}) -> {privateKey: string}

Request

  • username must control address.
  • address is the address for which you want to export the corresponding private key. It should be in hex format.

Response

  • privateKey is the CB58 endcoded string representation of the private key that controls address. It has a PrivateKey- prefix and can be used to import a key via avax.importKey.
  • privateKeyHex is the hex string representation of the private key that controls address. It can be used to import an account into Metamask.

Example Call

curl -X POST --data '{
    "jsonrpc":"2.0",
    "id"     :1,
    "method" :"avax.exportKey",
    "params" :{
        "username" :"myUsername",
        "password":"myPassword",
        "address": "0xc876DF0F099b3eb32cBB78820d39F5813f73E18C"
    }
}' -H 'content-type:application/json;' 127.0.0.1:9650/ext/bc/C/avax

Example Response

{
    "jsonrpc": "2.0",
    "result": {
        "privateKey": "PrivateKey-2o2uPgTSf3aR5nW6yLHjBEAiatAFKEhApvYzsjvAJKRXVWCYkE",
        "privateKeyHex": "0xec381fb8d32168be4cf7f8d4ce9d8ca892d77ba574264f3665ad5edb89710157"
    },
    "id": 1
}}

avax.getUTXOs

Gets the UTXOs that reference a given address.

Signature

avax.getUTXOs(
    {
        addresses: string,
        limit: int, //optional
        startIndex: { //optional
            address: string,
            utxo: string
        },
        sourceChain: string,
        encoding: string, //optional
    },
) -> 
{
    numFetched: int,
    utxos: []string,
    endIndex: {
        address: string,
        utxo: string
    }
}
  • utxos is a list of UTXOs such that each UTXO references at least one address in addresses.
  • At most limit UTXOs are returned. If limit is omitted or greater than 1024, it is set to 1024.
  • This method supports pagination. endIndex denotes the last UTXO returned. To get the next set of UTXOs, use the value of endIndex as startIndex in the next call.
  • If startIndex is omitted, will fetch all UTXOs up to limit.
  • When using pagination (ie when startIndex is provided), UTXOs are not guaranteed to be unique across multiple calls. That is, a UTXO may appear in the result of the first call, and then again in the second call.
  • When using pagination, consistency is not guaranteed across multiple calls. That is, the UTXO set of the addresses may have changed between calls.
  • encoding sets the format for the returned UTXOs. Can be either "cb58" or "hex". Defaults to "cb58".

Example

Suppose we want all UTXOs that reference at least one of C-avax1yzt57wd8me6xmy3t42lz8m5lg6yruy79m6whsf.

curl -X POST --data '{
    "jsonrpc":"2.0",
    "id"     :1,
    "method" :"avax.getUTXOs",
    "params" :{
        "addresses":["C-avax1yzt57wd8me6xmy3t42lz8m5lg6yruy79m6whsf"],
        "sourceChain": "X",
        "startIndex": {
            "address": "C-avax1yzt57wd8me6xmy3t42lz8m5lg6yruy79m6whsf",
            "utxo": "22RXW7SWjBrrxu2vzDkd8uza7fuEmNpgbj58CxBob9UbP37HSB"
        },
        "encoding": "cb58"
    }
}' -H 'content-type:application/json;' 127.0.0.1:9650/ext/bc/C/avax

This gives response:

{
    "jsonrpc": "2.0",
    "result": {
        "numFetched": "3",
        "utxos": [
            "11QEQTor9xZ1TyCyq8aFVShdP7YjM1ug9KuPUuMpgvQVz5qjEzo244NbJomjciNUPqUr1cD455dXhVrVNopnMXTQrTFY5kqrEVAQ3Ng9AnapQrYVEYiWc32F5CQuD3N5sB1EhQmMdJr5pis1QLjMmRQmut7Maafwup1vEU",
            "11Eo6c9iUz3ERtmHbdUb3nzzMaqFffFQStshEsSTiFQP5xqfmeaeCFHCBajmoJUdQRHtkChGAmPucDfuCyBAEyGmmv2w8b7dX5sATxV7HxHZE4eak14GMGVEr7v3ij1B8mE82cymTJJz1X3PpRk2pTaxwEnLWfh1aAiTFC",
            "118mpEHsia5sYYvKUx4j56mA7i1yvmLNyynm7LcmehcJJwMVY65smT4kGQgyc9DULwuaLTrUcsqbQutCdajoJXBdPVqvHMkYBTYQKs7WSmTXH8v7iUVqZfphMnS7VxVjGU1zykeTnbuAoZt4cFMUJzd8JaZk5eC82zmLmT"
        ],
        "endIndex": {
            "address": "C-avax1yzt57wd8me6xmy3t42lz8m5lg6yruy79m6whsf",
            "utxo": "27q6nsuvtyT4mvXVnQQAXw1YKoTxCow5Qm91GZ678TU1SvUiC2"
        },
        "encoding": "cb58"
    },
    "id": 1
}

avax.import

Finalize the transfer of a non-AVAX or AVAX from the X-Chain to the C-Chain. Before this method is called, you must call the X-Chain's avm.export method to initiate the transfer.

Signature

avax.import({
    to: string,
    sourceChain: string,
    username: string,
    password:string,
}) -> {txID: string}

Request

  • to is the address the asset is sent to. This must be the same as the to argument in the corresponding call to the C-Chain's export.
  • sourceChain is the ID or alias of the chain the asset is being imported from. To import funds from the X-Chain, use "X".
  • username is the user that controls to.

Response

  • txID is the ID of the completed ImportTx.

Example Call

curl -X POST --data '{
    "jsonrpc":"2.0",
    "id"     :1,
    "method" :"avax.import",
    "params" :{
        "to":"0x4b879aff6b3d24352Ac1985c1F45BA4c3493A398",
        "sourceChain":"X",
        "username":"myUsername",
        "password":"myPassword"
    }
}' -H 'content-type:application/json;' 127.0.0.1:9650/ext/bc/C/avax

Example Response

{
    "jsonrpc": "2.0",
    "result": {
        "txID": "6bJq9dbqhiQvoshT3uSUbg9oB24n7Ei6MLnxvrdmao78oHR9t"
    },
    "id": 1
}

avax.importAVAX

DEPRECATED—instead use avax.import

Finalize a transfer of AVAX from the X-Chain to the C-Chain. Before this method is called, you must call the X-Chain's avm.exportAVAX method to initiate the transfer.

Signature

avax.importAVAX({
    to: string,
    sourceChain: string,
    username: string,
    password:string,
}) -> {txID: string}

Request

  • to is the address the AVAX is sent to. It should be in hex format.
  • sourceChain is the ID or alias of the chain the AVAX is being imported from. To import funds from the X-Chain, use "X".
  • username is the user that controls to.

Response

  • txID is the ID of the completed ImportTx.

Example Call

curl -X POST --data '{
    "jsonrpc":"2.0",
    "id"     :1,
    "method" :"avax.importAVAX",
    "params" :{
        "to":"0x4b879aff6b3d24352Ac1985c1F45BA4c3493A398",
        "sourceChain":"X",
        "username":"myUsername",
        "password":"myPassword"
    }
}' -H 'content-type:application/json;' 127.0.0.1:9650/ext/bc/C/avax

Example Response

{
    "jsonrpc": "2.0",
    "result": {
        "txID": "LWTRsiKnEUJC58y8ezAk6hhzmSMUCtemLvm3LZFw8fxDQpns3"
    },
    "id": 1
}

avax.importKey

Give a user control over an address by providing the private key that controls the address.

Signature

avax.importKey({
    username: string,
    password:string,
    privateKey:string
}) -> {address: string}

Request

  • Add privateKey to username's set of private keys.

Response

  • address is the address username now controls with the private key. It will be in hex format.

Example Call

curl -X POST --data '{
    "jsonrpc":"2.0",
    "id"     :1,
    "method" :"avax.importKey",
    "params" :{
        "username" :"myUsername",
        "password":"myPassword",
        "privateKey":"PrivateKey-2o2uPgTSf3aR5nW6yLHjBEAiatAFKEhApvYzsjvAJKRXVWCYkE"
    }
}' -H 'content-type:application/json;' 127.0.0.1:9650/ext/bc/C/avax

Example Response

{
    "jsonrpc": "2.0",
    "result": {
        "address": "0xc876DF0F099b3eb32cBB78820d39F5813f73E18C"
    },
    "id": 1
}

avax.issueTx

Send a signed transaction to the network. encoding specifies the format of the signed transaction. Can be either "cb58" or "hex". Defaults to "cb58".

Signature

avax.issueTx({
    tx: string,
    encoding: string, //optional
}) -> {
    txID: string
}

Example Call

curl -X POST --data '{
    "jsonrpc":"2.0",
    "id"     : 1,
    "method" :"avax.issueTx",
    "params" :{
        "tx":"6sTENqXfk3gahxkJbEPsmX9eJTEFZRSRw83cRJqoHWBiaeAhVbz9QV4i6SLd6Dek4eLsojeR8FbT3arFtsGz9ycpHFaWHLX69edJPEmj2tPApsEqsFd7wDVp7fFxkG6HmySR",
        "encoding": "cb58"
    }
}' -H 'content-type:application/json;' 127.0.0.1:9650/ext/bc/C/avax

Example Response

{
    "jsonrpc":"2.0",
    "id"     :1,
    "result" :{
        "txID":"NUPLwbt2hsYxpQg4H2o451hmTWQ4JZx2zMzM4SinwtHgAdX1JLPHXvWSXEnpecStLj"
    }
}

avax.getAtomicTxStatus

Get the status of an atomic transaction sent to the network.

Signature

avax.getAtomicTxStatus({txID: string}) -> {
  status: string,
  blockHeight: string // returned when status is Accepted
}

status is one of:

  • Accepted: The transaction is (or will be) accepted by every node. Check the blockHeight property
  • Processing: The transaction is being voted on by this node
  • Dropped: The transaction was dropped by this node because it thought the transaction invalid
  • Unknown: The transaction hasn’t been seen by this node

Example Call

curl -X POST --data '{
    "jsonrpc":"2.0",
    "id"     :1,
    "method" :"avax.getAtomicTxStatus",
    "params" :{
        "txID":"2QouvFWUbjuySRxeX5xMbNCuAaKWfbk5FeEa2JmoF85RKLk2dD"
    }
}' -H 'content-type:application/json;' 127.0.0.1:9650/ext/bc/C/avax

Example Response

{
    "jsonrpc":"2.0",
    "id"     :1,
    "result" :{
        "status":"Accepted",
        "blockHeight": "1"
    }
}