⚠️ Important! We have recently released a major breaking rewrite for eosjs. Be sure to lock your dependencies. ⚠️

If you are looking for the the previous version of eosjs you can find it here.


Javascript API for integration with EOSIO-based blockchains using EOSIO RPC API.

Documentation can be found here



npm install eosjs@beta

Basic Usage


const eosjs = require('eosjs');
const fetch = require('node-fetch');                            // node only; not needed in browsers
const { TextDecoder, TextEncoder } = require('text-encoding');  // node, IE11 and IE Edge Browsers


SignatureProvider holds private keys and is responsible for signing transactions

const defaultPrivateKey = "5JtUScZK2XEp3g9gh7F8bwtPTRAkASmNrrftmx4AxDKD5K4zDnr"; // useraaaaaaaa
const signatureProvider = new eosjs.SignatureProvider([defaultPrivateKey]);


Open a connection to JSON-RPC, include fetch when on NodeJS

const rpc = new eosjs.Rpc.JsonRpc('', { fetch });

API Constructor

Include textDecoder and textEncoder when using in browser.

const api = new eosjs.Api({ rpc, signatureProvider, textDecoder: new TextDecoder, textEncoder: new TextEncoder });

Sending a transaction

(async () => {
  const result = await api.transact({
    actions: [{
      account: 'eosio.token',
      name: 'transfer',
      authorization: [{
        actor: 'useraaaaaaaa',
        permission: 'active',
      data: {
        from: 'useraaaaaaaa',
        to: 'useraaaaaaab',
        quantity: '0.0001 SYS',
        memo: '',
  }, {
    blocksBehind: 3,
    expireSeconds: 30,

Error handling

use eosjs_jsonrpc.RpcError for handling JSON-RPC Errors

try {
  const result = await api.transact({
} catch (e) {
  console.log('\nCaught exception: ' + e);
  if (e instanceof eosjs_jsonrpc.RpcError)
    console.log(JSON.stringify(e.json, null, 2);


After running npm run build-web or yarn build-web, the browser distribution will be located in dist. For full browser usage examples, see the documentation.

How it works

transact() is used to sign and push transactions onto the blockchain with an optional configuration object parameter. This parameter can override the default value of broadcast: true, and can be used to fill TAPOS fields given blocksBehind and expireSeconds. Given no configuration options, transactions are expected to be unpacked with TAPOS fields (expiration, ref_block_num, ref_block_prefix) and will automatically be broadcast onto the chain.

Running Tests

Automated Test Suite

npm run test or yarn test

Integration Tests

  1. npm run build-web or yarn build-web
  2. Open test.html in your browser of choice

The integration tests assume that you have a local node for EOS set up at localhost:8000. The test.html file should run through 5 test cases with the final showing an exception on the screen for missing required TAPOS.

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