Getting Started

A quick guide to getting started with developing on Harmony blockchain.

Overview

Harmony is a powerful blockchain that is EVM compatible with sharding and staking features. Developing on Harmony should feel very familiar for Ethereum developers, as Harmony is fully Ethereum compatible and inherits almost all the tools and libraries from Ethereum, like truffle, remix, web3js, etc.

The simplest way to interact with Harmony blockchain is via JSON RPCs.

Querying Harmony blockchain using JSON RPCs

• JSON RPCs and curl command examples

To really explore the full potential of Harmony blockchain, creating a wallet is the next step.

Creating a wallet (or ONE address)

• Using MetaMask or mathwallet browser extensions. Any other wallets can also be used.

• Harmony CLI, also provides a quick way to create/manage wallet, interact with blockchain, etc.

Harmony uses bech32 address format with one1 prefix, however Ethereum style hex address can also be used. For example: one1pdv9lrdwl0rg5vglh4xtyrv3wjk3wsqket7zxy bech32 address is equivalent to 0x0B585F8DaEfBC68a311FbD4cB20d9174aD174016 hex address. Quick way to convert between formats is using explorer: https://explorer.harmony.one/#/address/one1pdv9lrdwl0rg5vglh4xtyrv3wjk3wsqket7zxy, at the top you will find "ONE / ETH address" options.

Development environments

• Several development environments exists: mainnet, testnnet, localnet

• Testnet faucet

  • https://faucet.pops.one

  • https://chaindrop.org

• Blockchain Explorers

  • Mainnet: https://explorer.harmony.one

  • Testnet: https://explorer.testnet.harmony.one

We provide SDKs in several different languages. However most feature complete is our JavaScript SDK, which is the preferred language for DApp development.

Feel free to ping any POPS member for issues on the testnet network/explorer/faucet on harmony discord @harmony-pops or telegram P-OPS Team Validator Faucet can also be refilled by anyone by sending fund back to the contract address shown on https://faucet.pops.one

Using SDKs to interact with Harmony blockchain

• About SDKs

• The most popular is our JavaScript SDK, which includes examples, documentation, and DApps developed in previous hackathons

• Other SDKs include: Golang CLI, Java SDK, Python SDK

  • Note that, the Python SDK has only read-only features, meaning no transaction signing or smart contracts

How to deploy a smart contract on Harmony?

• Tutorial

• Github repo

• Interacting with wallets programmatically

How to create a simple DApp on Harmony?

One of the best ways to get started is to use scaffold-eth which now has integrated Harmony support.

You can also use the Harmony DApp template generator to get started.

• Tutorial

• GitHub repo

Many other examples and DApps can be found in the SDK repo and under showcases.

Resources

• talk.harmony.one - for reporting issues, asking questions, or interact with other developers

• Harmony GitHub

• Harmony dev Reddit

• Discord channels: #developers, #development

• Harmony dev Telegram

Known Limitations

• Only cross-shard native token (ONE token) transfers are allowed. No cross-shard for HRC20 or other contracts. Meaning, smart contracts are deployed on shard-0 and all contract interactions happen on shard-0. Contracts can still be deployed on other shards, however they won't be able to interact with contracts in other shards. We have cross-shard smart contract on our roadmap for 2023.