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Client library for Cosmos-SDK/Tendermint

Current state: 1.0.2 First major public release

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Built and maintenance by contributors and cyber•Congress


The easily scaled client library for creating, serializing and sending transactions for cosmos-sdk and tendermint based networks.

The library provides to use build-in methods for executing popular functions in Cosmos based networks or adding custom methods after creating message structure with js-amino.

The objective is providing query constructor to Cosmos community. By this way without additional efforts, it's an opportunity to supplement and customize existing classes of builders and RPC clients for interaction with any Cosmos based network by DRY and KISS principles.


  1. Separation of tx builder and server connection
  2. Gaia (Cosmos Hub) and Cyberd chains implemented
  3. OOP-based expandable architecture for supporting any type of cosmos or tendermint chains
  4. Possibility to redefine any step of transaction creation for custom networks like Cyberd
  5. Sending any default or custom transaction by one line by passing address, privateKey and transaction params
  6. Serialization using js-amino


  1. Implement Tendermint builder and RPC for generate and send transactions for general purposes that will be valid for any cosmos network without using cosmos-sdk (aka LCD, Gaia-Lite)
  2. Implement builders and RPC for popular cosmos networks
  3. Emulate RPC server in tests and test requests sending for RPC classes
  4. Improve tests coverage
  5. Ledger support
  6. Add more Gaia(Cosmos hub) methods


  1. Documentation


npm install js-cosmos --save

Usage example for Cosmos-sdk RPC

import CosmosSdkRpc from 'cosmos-js/dist/rpc/cosmosSdkRpc';
const constants = require('cosmos-js/dist/constants/cosmos');

const cosmosRpc = new CosmosSdkRpc('', constants);

const fromAddress = 'cosmos1adfp4t779mz5mqkp774l4d0umm2x9v4s42prxw';
const fromPrivateKey = 'a5b1305ebf29997a8a180b8bf322bc27b226e8cd00e243887e2129839c36bb2d';

const toAddress = 'cosmos14mgwf74me9jneaj7pxna873ufrqdwzes2vt4kl';
const amount = 1;

      address: fromAddress,
      privateKey: fromPrivateKey,

  .then(res => {
    console.log('res', res);

Usage example for Cyberd RPC

import CyberDRpc from 'cosmos-js/dist/rpc/cyberdRpc';

const constants = require('cosmos-js/dist/constants/cyberd');

const cyberdRpc = new CyberDRpc('', constants);

const fromAddress = 'cyber1adfp4t779mz5mqkp774l4d0umm2x9v4sjpxt05';
const fromPrivateKey = 'a5b1305ebf29997a8a180b8bf322bc27b226e8cd00e243887e2129839c36bb2d';

const toAddress = 'cyber14mgwf74me9jneaj7pxna873ufrqdwzesd8val9';
const amount = 1;

      address: fromAddress,
      privateKey: fromPrivateKey,

  .then(res => {
    console.log('res', res);

Custom builder definition

You might need use cosmos-sdk builder but with some custom RPC methods or with changes in transaction structure.

In this case - better to define your own builder that extends some exist builder like CosmosSdkBuilder.

For creating custom request - need to define js-amino type first of your custom message:

const { TypeFactory, Types } = require('js-amino');

const CustomMessage = TypeFactory.create('CustomMessage', [
    name: 'custom_address',
    type: Types.String,
    name: 'custom_amount',
    type: Types.String,

Then - you can use this CustomMessage for build custom request.

import CosmosSdkBuilder from 'cosmos-js/dist/builders/cosmosSdkBuilder';
import CosmosCodec from 'cosmos-js/dist/codec';

class MyCustomChainBuilder extends CosmosSdkBuilder {
  constructor() {
    // redefine codec for clear parent types and use only new types if you need
    this.codec = new CosmosCodec();
    this.codec.registerConcrete(new CustomMessage(), 'my-custom-chain/custom-message', {});
  myCustomRequest(sendOptions) {
    const msg = new CustomMessage(sendOptions.customAddress, sendOptions.customAmount);
    return this.abstractRequest(sendOptions, msg);

Then - you can build your request manually:

const requestData = {
  account: {
    address: keyPair.address,
    publicKey: keyPair.publicKey,
    privateKey: keyPair.privateKey,
    accountNumber: 0,
    sequence: 0,
  chainId: 'euler-4',
  customAddress: 'my-custom-address',
  customAmount: '999',
  fee: {
    denom: '',
    amount: '0',
  memo: ''

const customChainBuilder = new MyCustomChainBuilder();

const txRequest = customChainBuilder.myCustomRequest(requestData);

console.log('you can send result json to server:', txRequest.json);
console.log('or you can send result hex to server:', txRequest.hex);

Its already signed tx and converted to suitable for RPC server format.

If your RPC server takes non-standart data structures in Fee or Signature - you can redefine sendRequest, getResultTx, getFee, getSignature, getSignature, signMessageJson methods for write specific logic or data structure.

By this way - all your custom transactions will follow the same specific rules that defined in these methods.

You can see the example in cyberDBuilder.js.

Custom RPC definition

For definition method for sending your custom transaction to rpc server - you can create custom rpc class:

import CosmosSdkRpc from 'cosmos-js/dist/rpc/cosmosSdkRpc';

class MyCustomChainRpc extends CosmosSdkRpc {
  constructor(rpc, constants) {
    super(rpc, constants);
    this.cosmosBuilder = new MyCustomChainBuilder();
  async executeCustomRequest(txOptions, customAddress, customAmount) {
    const options = await this.prepareOptions(txOptions, {
      // for using inside myCustomRequest
      // you can also redefine fee for example
      fee: {
        denom: 'uatom',
        amount: '500',

    // calling previously defined myCustomRequest
    const txRequest = this.cosmosBuilder.myCustomRequest(options);
    // sending to server
    return this.handleResponse(`${this.rpc}/txs`, {
       tx: JSON.parse(txRequest.json),
       mode: 'sync',

Then use MyCustomChainRpc like this:

const myCustomChainRpc = new MyCustomChainRpc('http://rpc.server', new NetConfig('customprefix', 'custompubprefix'));

    {privateKey: 'a5b1305ebf29997a8a180b8bf322bc27b226e8cd00e243887e2129839c36bb2d'}, 
).then(res => {
    console.log('res', res);

Gitcoin program

We want to pay you for your contribution! We constantly fund our issues on gitcoin and attach good description for them with project state and user stories. We try to answer to comments regular in issues and in our devChat.

Contributing Guide

Guys, we appreciate your issues and features request, please leave your feedback if you are going to use or developing using this library.

Contribution are welcome! Please read this guide before contributing.


Thanks goes to these wonderful people (emoji key):


💻 ⚠️ 📖 🚧
Ales Puchilo
Ales Puchilo


Valery Litvin
Valery Litvin

💻 📆 📖

This project follows the all-contributors specification. Contributions of any kind welcome!

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