A mainnet is the main blockchain network on which cryptocurrencies are transacted. Whereas a testnet is a replica of the mainnet with reduced security and reduced network capacity.
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Why create a separate Testnet?
Testnets are akin to sandboxes in software development. They are used to test a feature which is not yet implemented on the main blockchain. These testnets are a way to test blockchain features and even DApps that are about to go live on the mainnet.
A testnet is a cheaper way to simulate the working of the mainnet because of several reasons.
The first reason is that the testnet requires much lesser security than the mainnet. For example,. in Ethereum the mainnet has around 900k validators while the Goerli testnet has only aboout 1800 validators.
A second reason is testnet cryptocurrencies such as Sepolia ETH or Goerli ETH are available for free and therefore are worthless. Also Testnet ETH cannot be converted into Mainnet ETH.
#NOTE: During shortages, Gloerli ETH happens to be sold to the developers who need it to test their Dapps.
List of Ethereum Testnets
Only Ethereum testnets bear a different name because Ethereum has more than one testnet. Another testnet with its own unique name is Polygon’s Mumbai.
In other cases, the testnet bears the same name as the mainnet with just the word “testnet” suffixed to it.
- Goerli – deprecated
- Rinkeby -Sunsettted
- Kovan – Sunsetted
#NOTE: Sunsetted means the project is permanently shut down. Deprecated means it is out of use and could be soon shut down.
How to Add a Testnet to MetaMask?
Testnets have to be added as custom networks in MetaMask.
Currently only Sepolia and Holesky testnets are active in Ethereum. Others have either been deprecated or sunsetted.
Ethereum – Sepolia Testnet
To add Sepolia Testnet to MetaMask, click on impport token and then select custom import. Add the following details to add the testnet.
- Network Name: Sepolia Test Network
- New RPC URL: https://sepolia.infura.io/v3/
- Chain ID: 11155111
- Currency Symbol: SepoliaETH
- Block Explorer URL: https://sepolia.etherscan.io
Ethereum – Holesky
- Network Name: Holesky
- New RPC URL: https://rpc.holesky.ethpandaops.io
- Chain ID: 17000
- Currency Symbol: ETH
- Block Explorer URL: https://dora.holesky.ethpandaops.io/
Polygon Testnet – Mumbai
- Network Name: Mumbai Testnet
- New RPC URL: https://rpc-mumbai.maticvigil.com/
- Chain ID: 80001
- Currency Symbol: MATIC
- Block Explorer URL: https://polygonscan.com/
Frequently Asked Questions
How do I get Testnet ETH for Ethereum?
You can get testnet ETH from the following faucets:
1. Goerli Faucet
2. Moralis Web3
How do I start developing on Ethereum Testnet?
You need to learn Solidity to create smart contracts and basic programming to design the frontend of the DApp on Ethereum.
After that you can add some testnet ETH to your wallet. Make sure not to send real ETH to testnet otherwise it will lead to a loss.
Develop a smart contract using Remix IDE or any other Solidity IDE.
Go to Goerli.Net or any other testnet terminal to deploy your DApp.
Do all blockchains have Testnet?
Yes, a testnet is necessary to test the blockchain features. Therfore, most blockchains do have an active testnet.