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 onewallet 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.

Development environments

• Several development environments exists: mainnet, testnnet, localnet​

• Testnet faucets

  • ​https://faucet.pops.one/

  • ​https://onefaucet.ibriz.ai/​

• Blockchain Explorers

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

  • Testnet: https://explorer.pops.one/​

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

Using SDKs to interact with Harmony blockchian

• 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 Q3, 2021.