What Is A Testnet? Blockchain Testnets Explained

Testnet is a blockchain network identical to the main network used for testing and experimenting with new features. These testnets allow developers to find potential network issues and errors and fix them before deploying them on the mainnet. 

The cyber attackers exploit smart contract flaws to steal the project's funds. For example, Hedgey Finance lost over $44 million in April 2024 as hackers misused the smart contract vulnerabilities on their Arbitrum and Ethereum networks. 

Smart contract security vulnerabilities, like logical flaws, enable security attacks that can lead to the loss of millions of users' funds and credibility issues among the crypto community. Testnets emerges as a solution to find and fix glitches and to build more feature-rich dApps for users.

What is a Testnet?

A testnet or test network is a type of network that can provide functionalities similar to that of a main network (mainnet). Developers can use testnet as a simulated version of mainnet to test, modify, or create projects on blockchain networks. 

Testing or implementing new features on the mainnet can be highly risky and irreversible in case of any errors. So, blockchain developers first conduct the trials on the testnet to monitor the functioning before adding it live on the mainnet. 

Testnets, therefore, play a crucial role in advancing blockchain projects. For example, if a dApp needs refinement, developers can experiment with different options on a testnet and even ask for feedback from their community before implementation. 

You can also utilize incentivized testnets to earn token rewards for validating, testing, or providing feedback on the performance, security, and user interference of blockchain projects. For example, Aptos blockchain platform offered 800 token rewards to participants for completing all their incentivized testnet objectives on time.

What are the Features of Testnets?

Free Tokens

Testnet offers free crypto tokens that don't have any value elsewhere. The sole aim behind providing such tokens is to use them for testing activities within that particular testnet. 

For example, the BNB Smart Chain network offers users free Testnet BNB (tBNB) tokens. However, these tokens have no real value and can only be used for testing and developing on its blockchain network.

Isolated Testing and Development

The testnet is isolated from the blockchain ecosystem, including its mainnet. The changes or experiments applied on the testnet don't impact the mainnet of that blockchain network. 

This isolation feature allows blockchain projects to try and test innovative features. Moreover, the developers can also provide heavy loads to check the network's efficiency without stopping the mainnet's functions.

Faster Execution

The activities executed are faster as testnets are simpler than the live blockchain network. For this reason, the transactions on the testnet are confirmed faster, allowing developers to conduct numerous tests within a limited time. 

The faster execution feature allows developers to mint free coins easily on testnets. This privilege of mining different free coins helps to experiment on utility tokens with varied characteristics till they find the ideal one.

Varied Consensus Mechanisms

Testnet allows developers to deploy different consensus mechanisms that suit their project. The option to choose a consensus mechanism allows developers to find the one that suits the best for their platform or dApp.

Here, developers can deploy multiple consensus mechanisms like Proof of Stake (PoS), Proof of Work (PoW), or proof of authority (PoA) on multiple testnets at a time. Finally, the development team can analyze the result and deploy the appropriate one on their mainnet.

Strong Community Support

Community is an important element for blockchain-based projects, and it's no different regarding testnet. Testnets that work on prominent blockchain networks, such as Ethereum, Solana, etc, are supported by its community members through online platforms. 

Developers can ask for help from the community to test their dApps or other crypto platforms and provide feedback. The developers can also collaborate to test new products on testnet that require higher expertise.

Popular Examples of Testnets

Here is a list of popular testnets from prominent blockchain networks:

1. Rinkeby: This Ethereum testnet was introduced in 2017 on a Proof of Authority (PoA) consensus mechanism to confirm network transactions. Developers used this deprecated testnet to test their smart contracts with the free testnet ETH tokens. 
2. Kovan: Introduced in 2017, this deprecated Ethereum testnet also functioned using the PoA consensus mechanism, allowing developers to write smart contracts for tokens standards like ERC-20, ERC-721, and ERC-1155. Kovan testnet offered Kovan Ether, a crypto token used for testing on the Ethereum blockchain.  
3. Ropsten: This older Ethereum testnet was launched in late 2016 with a proof of work (PoW) consensus mechanism that allowed developers to test and evaluate security vulnerabilities on a network. However, this testnet was shut down following a security attack in early 2017.   
4. Goerli: Officially launched in 2019, this was the first community-built Ethereum testnet with a PoA consensus mechanism. This deprecated testnet provided developers a more reliable and stable environment to build and test various dApps.
5. Sepolia: Created by Ethereum core developers in late 2021, the Sepolia testnet transitioned from PoA to PoS consensus mechanism when  Ropsten attained 5 trillion terminal total difficulty (TTD). This testnet has a shorter block time and was developed to provide faster feedback and validate transaction details for testing developers. 
6. Kusama: Founded in 2019, Kusama is the official testnet of the Polkadot ecosystem that allows developers to test features, including governance, without disturbing the mainnet. Kusama has its native token, KSM, which allows developers to pay and test various functionalities in the blockchain network.    
7. Solana Devnet: This testnet is specifically designed for the Solana blockchain to help developers to experiment with various features, including token creation, deploying smart contracts, or modifying dApps. Developers can use simulated SOL tokens to test different features on the Solana Devnet without risking any real SOL tokens.

How Does a Testnet Work?

The testnet starts working once the developers upload new updates or features to analyze its performance. Here, they check for possible errors in the codebase as part of the debugging process. 

After completing the debugging process, the edited codes are launched in a contained environment, sandbox. This launch facilitates the testing of the configurations and monitors the operation. 

The proper functioning of the testing process requires free testnet tokens as gas fees. However, even though these tokens are free, they are limited in supply as the liquidity of the testnet is lower compared to that of its mainnet liquidity. 

Here, the computational load required for running the testnet also varies based on various factors like the selected consensus mechanism. The testing of complex smart contracts or dApps also increases the load on the testnet.

How to Build on a Testnet?

For Users

First, you need to choose a testnet or required blockchain network that allows them to conduct a test. For example, if you want to conduct tests on the Polygon network, you can opt for its latest Amoy testnet. 

Once the testnet network is selected, users are required to connect wallets that support their chosen network. If you're experimenting on numerous projects, it's best to use a multi-chain crypto wallet like Atomic Wallet or MetaMask that supports multiple blockchain networks. 

After connecting the wallet, users need to collect free testnets tokens from its crypto faucet. This minimal amount of tokens has no monetary value but can be used to interact with the network to test functions like paying gas fees. 

Users can participate in identifying glitches in the task as a part of a bug bounty program conducted by projects. The developers work to fix the issues according to user feedback and reward the eligible users.

For Developers

To build on a testnet, developers need to opt for a testnet that is ideal for their dApp or platform. Next, they need to create one or more testnet wallets based on their testing requirements. 

The developers then need to visit Testnet faucets that provide compatible testnet crypto tokens for their network. These tokens play a crucial role in paying to validate transactions or gas fees while conducting various tests on the network.

Next, the developers can start testing once their wallet is connected and testnet coins are credited. Before experimenting with complex functionalities, it's better to conduct minor features to check the working condition of the testnet. 

Once the sample test is successful, developers can carry forward with multiple complex testing processes. For example, a team of developers can conduct unit testing for smart contracts where each component is individually tested to ensure proper functioning. 

The testing is not limited to smart contracts, as developers can also test their dApp to improve efficiency. If a new dApp is taking more time to connect with users' wallets, developers can work on testnet to solve that issue without affecting the ongoing mainnet activities. 

Developers can also collect feedback from community members about their platform or dApp. At last, the development team can choose major issues, check them on the testnet, and fix the glitches on the mainnet to provide a better user experience.

Differences Between Testnet and Mainnet

The main difference between testnet and mainnet includes the following: 

 

Parameters	Testnet	Mainnet
Purpose	It offers a simulation platform for testing smart contracts or dApps.	Allows processing of real transactions on the main blockchain network.
Tokens	Tokens have no value in the blockchain ecosystem.	Uses real tokens with monetary value in the crypto marketplace.
Risks	Limited security and financial risks involved.	Security issues can lead to high financial loss and credibility.
Mining Benefits	No economic benefit for miners.	Miners have the potential to generate economic benefits.
Bug Bounties	Fewer rewards for finding security vulnerabilities.	Huge rewards for finding major security flaws.

Conclusion

Testnet plays a crucial role in fostering the blockchain ecosystem by allowing developers to experiment with new features using free testnet coins. Testnet also helps to find and fix security vulnerabilities on a blockchain network. 

Most importantly, the experiments on the testnet don't affect the mainnet. This risk-free testing feature of testnet encourages the development team to fine-tune their platform or dApp to maximize user satisfaction.