Blockchain development requires seamless interaction with various networks, each having unique identifiers and connection endpoints. Whether you're deploying smart contracts, building decentralized applications (dApps), or testing transactions, knowing the correct ChainID, RPC URL, and block explorer for each network is crucial. This guide compiles essential information across major blockchain ecosystems—including Ethereum, Polygon, Avalanche, xDai, and Shiden—to streamline your development workflow.
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Understanding ChainID and RPC URLs
Before diving into specific networks, let’s clarify two foundational concepts:
- ChainID: A unique identifier used to distinguish one blockchain network from another. It prevents transaction replay attacks across chains and is required when configuring wallets like MetaMask.
- RPC URL (Remote Procedure Call): The endpoint that allows your application or wallet to communicate with a blockchain node. Without a valid RPC URL, your dApp can't read blockchain data or send transactions.
These values are essential whether you're coding in Solidity, using Web3.js/ethers.js, or simply adding a custom network to your wallet.
Ethereum Networks
Ethereum remains the most widely used blockchain for decentralized applications. Below are its main and test networks.
Mainnet
- ChainID (Decimal): 1
- ChainID (Hex): 0x1
- Network Name: Ethereum Main Network
- RPC URL:
https://mainnet.infura.io/v3/ - Block Explorer: Etherscan
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Ropsten Testnet (Deprecated)
- ChainID (Decimal): 3
- ChainID (Hex): 0x3
- Network Name: Ropsten Test Network
- RPC URL:
https://ropsten.infura.io/v3/ - Block Explorer: Ropsten Etherscan
⚠️ Note: Ropsten has been deprecated after the Ethereum Merge. Developers should migrate to Goerli or Sepolia.
Rinkeby Testnet (Deprecated)
- ChainID (Decimal): 4
- ChainID (Hex): 0x4
- RPC URL:
https://rinkeby.infura.io/v3/ - Block Explorer: Rinkeby Etherscan
⚠️ Rinkeby is no longer supported for new testnet activities.
Goerli Testnet
- ChainID (Decimal): 5
- ChainID (Hex): 0x5
- Network Name: Goerli Test Network
- RPC URL:
https://goerli.infura.io/v3/ - Block Explorer: Goerli Etherscan
Kovan Testnet (Deprecated)
- ChainID (Decimal): 42
- ChainID (Hex): 0x2a
- RPC URL:
https://kovan.infura.io/v3/ - Block Explorer: Kovan Etherscan
✅ Recommendation: Use Goerli or Sepolia for current Ethereum testing.
Polygon Networks
Polygon (formerly Matic) offers scalable solutions for Ethereum-compatible dApps.
Polygon Mainnet
- ChainID (Decimal): 137
- ChainID (Hex): 0x89
- Network Name: Polygon Mainnet
- RPC URL:
https://rpc-mainnet.maticvigil.com/ - Block Explorer: Polygonscan
Mumbai Testnet
- ChainID (Decimal): 80001
- ChainID (Hex): 0x13881
- Network Name: Mumbai Testnet
- RPC URL:
https://rpc-mumbai.maticvigil.com/ - Block Explorer: Mumbai Polygonscan
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xDai Networks
xDai is an Ethereum-based stablecoin-powered chain focused on low fees and fast transactions.
xDai Mainnet
- ChainID (Decimal): 100
- ChainID (Hex): 0x64
- Network Name: xDai Mainnet
- RPC URL:
https://rpc.xdaichain.com/ - Block Explorer: Blockscout xDai
Sokol Testnet
- ChainID (Decimal): 77
- ChainID (Hex): 0x4d
- Network Name: Sokol Testnet
- RPC URL:
https://sokol.poa.network/ - Block Explorer: Sokol Blockscout
Shiden Networks
Shiden is a multi-chain platform on the Kusama network, supporting Ethereum-, WASM-, and Layer2-compatible dApps.
Shiden Mainnet
- ChainID (Decimal): 336
- ChainID (Hex): 0x150
- Network Name: Shiden Mainnet
- RPC URL:
https://rpc.shiden.astar.network:8545/ - Block Explorer: Shiden Subscan
Shibuya Testnet
- ChainID (Decimal): 81
- ChainID (Hex): 0x51
- Network Name: Shibuya Network (Parachain Testnet)
- RPC URL:
https://rpc.shibuya.astar.network:8545 - Block Explorer: Shibuya Subscan
Avalanche Networks
Avalanche is known for its high throughput and sub-second finality, making it ideal for DeFi and NFT projects.
Avalanche C-Chain Mainnet
- ChainID (Decimal): 43114
- ChainID (Hex): 0xa86a
- Network Name: Avalanche Mainnet C-Chain
- RPC URL:
https://api.avax.network/ext/bc/C/rpc - Block Explorer: Snowtrace
Fuji Testnet
- ChainID (Decimal): 43113
- ChainID (Hex): 0xa869
- Network Name: Avalanche Fuji C-Chain
- RPC URL:
https://api.avax-test.network/ext/bc/C/rpc - Block Explorer: Snowtrace Testnet
Frequently Asked Questions
What is a ChainID and why does it matter?
A ChainID uniquely identifies a blockchain network. It ensures transactions are valid only on their intended chain, preventing cross-chain replays. For example, sending a transaction signed for Ethereum Mainnet (ChainID 1) will fail on Polygon (ChainID 137).
How do I add a custom network to MetaMask?
In MetaMask, go to "Settings" > "Networks" > "Add Network", then enter:
- Network Name
- New RPC URL
- ChainID
- Currency Symbol
- Block Explorer URL
Ensure all fields match the target network exactly.
Are Infura RPC URLs free to use?
Yes, Infura offers a free tier suitable for development and small-scale applications. However, for production-grade dApps requiring high uptime and low latency, consider upgrading or using alternative providers.
Why are some Ethereum testnets deprecated?
After Ethereum’s transition to proof-of-stake (The Merge), older testnets like Ropsten, Rinkeby, and Kovan were phased out. Newer testnets like Goerli and Sepolia use PoS and better reflect the current Ethereum environment.
Can I use the same wallet address across different networks?
Yes! Your Ethereum wallet address works across all EVM-compatible chains. However, balances and transaction history are separate per network.
How often do ChainIDs change?
ChainIDs never change once assigned. They are hardcoded into the protocol and remain constant throughout a network’s lifecycle.
This guide provides accurate, up-to-date information on key blockchain networks used in modern dApp development. By referencing this resource, developers can avoid configuration errors, speed up integration, and focus on building innovative decentralized solutions. Always verify URLs and ChainIDs before deployment—especially in production environments.