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  • Supported Chains
  • Harmony

Harmony

Harmony is a powerful EVM compatible blockchain with sharding and staking features.

Developing on Harmony should be familiar for Ethereum developers, as it is fully Ethereum compatible and inherits almost all the tools and libraries from Ethereum, like truffle, remix, web3js, etc.

Quick links

Harmony

Docs

Github

Connect wallet

You can set up your MetaMask wallet to connect to Celo RPC. You can then perform transactions and interact with the network.

Get started

  1. Open your Metamask Extension and click the 'Network' drop down menu at the top.
  2. Select 'Custom RPC'.
  3. Enter the settings for the required project as follows in the table below:
ChainCustom RPC CategoryDetails
CeloNETWORK NAME:Harmony RPC
NEW RPC URL:https://rpc.ankr.com/harmony/
CHAIN ID:1666600000 (shard 0)
SYMBOL:ONE
BLOCK EXPLORER URL:https://explorer.harmony.one/

Integrate code

All requests follow the standard JSON-RPC format and include 4 variables in the data object:

Request Data ObjectExamplePurpose
Jsonrpc"2.0"Specifies version number
Method"hmy_getBalance"Method to be called server-side
Params["0xD7Ff...24Cf2d", "latest"]Parameters for method call

Key Differences between Harmony and Ethereum

  1. The prefix of RPC calls is different - 'hmy' for API v1 or 'hmyv2' for API v2 is used instead of 'eth'.

  2. Address format - Harmony uses bech32 address format with one1 prefix. The Ethereum style hex address can also be used. For example: one1pdv9lrdwl0rg5vglh4xtyrv3wjk3wsqket7zxy bech32 address is equivalent to 0x0B585F8DaEfBC68a311FbD4cB20d9174aD174016 hex address. A 1uick way to convert between formats is using the explorer: https://explorer.harmony.one/#/address/one1pdv9lrdwl0rg5vglh4xtyrv3wjk3wsqket7zxy. The top shows "Address Format" ONE | ETH options.

  3. Harmony transactions are encoded using RLP with two additional fields for shard ids. The purpose of RLP (Recursive Length Prefix) is to encode arbitrarily nested arrays of binary data. It is the main encoding method used to serialize objects in Ethereum.

rlp takes a String, int or List and returns an RLP encoded Uint8List with two additional fields to represent from and to shard ids (shardID and toShardID)

web3 library

  • clientVersion

Returns the current client version.

Example request

curl https://rpc.ankr.com/harmony \
  -X POST \
  -H "Content-Type: application/json" \
  --data '{"jsonrpc":"2.0","method":"web3_clientVersion","params":[],"id":1}'

Example response

{"jsonrpc":"2.0","id":1,"result":"Harmony (C) 2020. harmony, version v7331-v4.3.4-0-g4ea9072e (runner@ 2022-01-31T03:01:13+0000)"}

net library

  • net_version

Returns the current network id.

Example request

  
  curl https://rpc.ankr.com/harmony\
  -X POST \
  -H "Content-Type: application/json" \
  --data '{"jsonrpc":"2.0","method":"net_version","params":[],"id":67}'

Example response

{"jsonrpc":"2.0","id":67,"result":"1666600000"}

eth library

Harmony fully supports most eth_ calls in a slightly different way. For example, it uses hmyv2_ instead of eth_.

Below are some example requests. You can also View the full Harmony APIv2 Documentation.

Example request

Get current block number

curl https://rpc.ankr.com/harmony\
  -X POST \
  -H "Content-Type: application/json" \
  --data '{"jsonrpc":"2.0","method":"hmyv2_blockNumber","params":[],"id": 1}'

Example response

{"jsonrpc":"2.0","id":1,"result":25548421}
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