The purpose of this page is to give you a sense of everything js-conflux-sdk can do and serve as a quick reference guide


  1. 1.
    Node.js environment to install this SDK
  2. 2.
    Conflux account with some CFX (Use FluentWallet to create account and get testnet CFX from faucet)
  3. 3.
    Conflux RPC endpoint, for example is a testnet RPC endpoint


After installing js-conflux-sdk (via npm), you’ll need to specify the provider url. You can use the mainnet(, or testnet(, or run your own Conflux node.


With a RPC endpoint we can initialize a Conflux object, which can be used to send JSON RPC request.
const { Conflux } = require('js-conflux-sdk');
// initialize a Conflux object
const conflux = new Conflux({
url: '',
logger: console, // for debug
networkId: 1, // networkId is also need to pass
// Conflux class also have a static method `create`, can be used to create a new instance with no need to set networkId option
async function main() {
const conflux = await Conflux.create({
url: "",
Besides url and logger you can pass other options to initialize a Conflux object

Add account

Private keys are required to approve any transaction made on your behalf, conflux.wallet provide utility help you manage your accounts
Only after you add your account to wallet, then you can use them send transactions.

Send JSON-RPC request

There are a lot methods on cfx object which are one-to-one with Conflux node RPC methods. All conflux methods will return a promise, so you can use it with async/await syntax.
async function main() {
// get balance
const balance = await conflux.cfx.getBalance('cfxtest:aak2rra2njvd77ezwjvx04kkds9fzagfe6d5r8e957');
console.log(balance.toString()); // 10098788868004995614504
Besides balance you can get a lot blockchain information through it, for example: nonce, block, transaction, receipt and so on. You can check API and RPC

Conflux hex address

Note: from Conflux-rust v1.1.1 we have import a new base32 encoded address, the hex address can not be used then.
In Conflux network there are three kind address:
  • Normal address 0x1 prefix: 0x1386B4185A223EF49592233b69291bbe5a80C527
  • Contract address 0x8 prefix: 0x80a17fd515c1fc819e87e606c058490ac1f14ca7
  • Internal contract address 0x0888 prefix: 0x0888000000000000000000000000000000000000
So normally a ethereum's address cann't used as conflux address, otherwise it starts with 0x1
Notice: one address can have two form checksumed and not checksumed, these two actually are same account. For example 0x1386B4185A223EF49592233b69291bbe5a80C527 and 0x1386b4185a223ef49592233b69291bbe5a80c527 which point to same account.

Conflux base32 checksum address

From conflux-rust 1.1.1 Conflux has switch to base32Checksum address for example cfxtest:aak2rra2njvd77ezwjvx04kkds9fzagfe6d5r8e957. It was introduced by CIP37. js-conflux-sdk add support for it from version 1.5.10, check here for details.

Send Transaction

// first add account's private key to wallet
const account = conflux.wallet.addPrivateKey('0xxxxxxxxxx');
const targetAddress = 'cfxtest:xxxxxxx';
let hash = await conflux.cfx.sendTransaction({
from: account.address,
to: targetAddress,
value: 1 // the unit is drip
// check tx status through it's hash
let transaction = await conflux.cfx.getTransactionByHash(hash); // normally need half minute to get transaction info
Check here for details


chainId is used to distinguish different network and prevent replay attack, currently:
  • mainnet: 1029
  • testnet: 1

RPC endpoint

Hex value and epochNumber and tags

You can find the epochNumber doc at official developer RPC doc


Because in blockchain world there are a lot big numbers (uint256), only modern JS VM and Node.js support BigInt, so we use JSBI in browser environment to handle these big number. For how to use JSBI check it's documentation
Note: jsbi currently cann't pretty log, you need convert it to string before log.
const max = JSBI.BigInt(Number.MAX_SAFE_INTEGER);
// → '9007199254740991'
console.log(max.toString()); // directly log a jsbi is very ugly
// JSBI(2) [ -1, 2097151, sign: false ]
Note: When a js integer is bigger than Number.MAX_SAFE_INTEGER (2^53 - 1 or 9,007,199,254,740,991) you should use BigInt to contain it.


In Conflux network there are there unit: CFX, Drip, Gdrip. Drip is the minimum unit in Conflux 1 CFX=10^18Drip, 1Gdrip=10^9Drip. When getting account's balance, send transaction, specify gasPrice, all unit will be Drip. The SDK has provide a class Drip, which can use to easily convert between different unit.
import {Drip} from "js-conflux-sdk"
let drip1 = Drip.fromCFX(1);
// 1000-000-000-000-000-000
let drip2 = Drip.fromGDrip(1);
// 1000-000-000
let drip3 = new Drip(1);
// 1
// 1
// 1000-000-000

Websocket provider

The SDK also provide a websocket provider, and the default Conflux node ws port is 12535.
const { Conflux } = require('js-conflux-sdk');
async function main() {
// initialize a Conflux object
const conflux = new Conflux({
url: 'ws://localhost:12535',
logger: console, // for debug
// get balance
const balance = await conflux.cfx.getBalance('cfxtest:aak2rra2njvd77ezwjvx04kkds9fzagfe6d5r8e957');
console.log(balance.toString()); // 10098788868004995614504
// you need manual close the websocket connection


Conflux node support pub/sub makes it possible to query certain items on an ongoing basis, without polling through the JSON-RPC HTTP interface, currently three topics are supported: newHeads, epochs, logs, for detail explain of Pub/Sub check the official doc
Use JS SDK it will be very easy to use Pub/Sub.
const { Conflux } = require('js-conflux-sdk');
async function main() {
const conflux = new Conflux({
url: 'ws://localhost:12535',
// sub
let newHeadEmitter = await conflux.subscribeNewHeads();
newHeadEmitter.on('data', console.log);
let logEmitter = await conflux.subscribeLogs();
logEmitter.on('data', console.log);
let epochEmitter = await conflux.subscribeEpochs();
epochEmitter.on('data', console.log);
// unsubscribe

Interact with contract

Quick demo of interact with contract: query balance of one CRC20 token
async function main() {
const FC_ADDRESS = "cfx:achc8nxj7r451c223m18w2dwjnmhkd6rxawrvkvsy2";
const contract = conflux.CRC20(FC_ADDRESS);
const balance = await contract.balanceOf('cfxtest:aak2rra2njvd77ezwjvx04kkds9fzagfe6d5r8e957');
console.log(`FC balance: ${balance}`);
You can use this SDK get and update contract state, we have a complete documentation for you.

Type conversion

If you want convert a hex to number, or uint, you can use format, for example:
const { format } = require('js-conflux-sdk');
// 16
// 0n
// "0x01"


The SDK also provide most common used crypto utilities in sign
const { sign } = require('js-conflux-sdk');
// generate a random buffer
let buf = sign.randomBuffer(0);
let keccakHash = sign.keccak256(buf);
// random generate a private key
let privateKey = sign.randomPrivateKey(buf);
// get public key from private key
let pubKey = sign.privateKeyToPublicKey(privateKey);
// get address from public key
let address = sign.publicKeyToAddress(pubKey);
// use private key sign (ecdsa) a buffer
let signResult = sign.ecdsaSign(buf, privateKey);
// recover public key from signature and buf, then convert it to address
sign.publicKeyToAddress(sign.ecdsaRecover(buf, sign.ecdsaSign(signResult, privateKey)))