API libraries and interfaces for communicating with Polkadot and Substrate nodes


A powerful dynamic API that allows chain interactions with transparent encoding and decoding.

Substrate defaults

An overview of the various default methods, state entries and RPCs for Substrate-based chains.


Various type interfaces to make using returned values from API calls transparent in your code.


The API provides application developers the ability to query a node and interact with the Polkadot or Substrate chains using Javascript. Here you will find documentation and examples to get you started.


In a rush and just want examples? Jump right in and get a handle on using the API in your projects.

Available packages

This repository split up into a number of internal packages, namely -

  • api Promise and RxJS-based APIs
  • types Type encoding and decoding wrappers

The Polkadot Project

You can read more about the Polkadot Network at https://polkadot.network/ and more about the polkadot-js projects at https://polkadot.js.org

Github repositories

You can find the Polkadot repositories at:

This documentation is generated from https://github.com/polkadot-js/api


Contribution to the Polkadot JS API are more than welcome. You can report issues and log feature requests.