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AvalancheJS Overview

AvalancheJS is a JavaScript Library for interfacing with the Avalanche platform. It is built using TypeScript and intended to support both browser and Node.js. The AvalancheJS library allows one to issue commands to the Avalanche node APIs.

The APIs currently supported by default are:

  • Admin API
  • Auth API
  • AVM API (X-Chain)
  • EVM API (C-Chain)
  • Health API
  • Index API
  • Info API
  • Keystore API
  • Metrics API
  • PlatformVM API
  • Socket API

We built AvalancheJS with ease of use in mind. With this library, any JavaScript developer is able to interact with a node on the Avalanche Platform who has enabled their API endpoints for the developer’s consumption. We keep the library up-to-date with the latest changes in the Avalanche Platform Specification found in the Platform Chain Specification, Exchange Chain (X-Chain) Specification, Contract Chain (C-Chain) Specification.

Using AvalancheJS, developers can:

  • Locally manage private keys
  • Retrieve balances on addresses
  • Get UTXOs for addresses
  • Build and sign transactions
  • Issue signed transactions to the X-Chain, P-Chain and C-Chain on the Primary network
  • Create a Subnetwork
  • Swap AVAX and assets between the X-Chain, P-Chain and C-Chain
  • Add a Validator to the Primary network
  • Add a Delegator to the Primary network
  • Administer a local node
  • Retrieve Avalanche network information from a node


AvalancheJS requires Node.js version 14.18.0 or higher to compile.


Avalanche is available for install via npm or yarn. For installing via npm:

npm install --save avalanche

For installing via yarn:

yarn add avalanche

You can also pull the repo down directly and build it from scratch:

npm run build

This will generate a pure JavaScript library and place it in a folder named "web" in the project root. The "avalanchejs" file can then be dropped into any project as a pure JavaScript implementation of Avalanche.

The AvalancheJS library can be imported into your existing Node.js project as follows:

const avalanche = require("avalanche")

Or into your TypeScript project like this:

import { Avalanche } from "avalanche"

Importing Essentials

import { Avalanche, BinTools, Buffer, BN } from "avalanche"

let bintools = BinTools.getInstance()

The above lines import the libraries used in the tutorials. The libraries include:

  • avalanche: Our JavaScript module.
  • bn.js: A big number module use by AvalancheJS.
  • buffer: A Buffer library.
  • BinTools: A singleton built into AvalancheJS that is used for dealing with binary data.