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What is a Testnet?

A testnet is an identical copy of a blockchain network that is created for the sole purpose of testing out new products and features.


It operates as a development hotbed where developers can try out new functionalities before integrating them into the main blockchain network – termed the mainnet.

For individuals interested in acquiring new skills and exploring different features without using the primary blockchain network, a testnet provides a safety net.

Techopedia Explains

Launching new products or features directly on a live blockchain comes with risks, as certain vulnerabilities may go unnoticed.

Such oversights could result in financial losses for investors or even make the blockchain network susceptible to external threats if an access point is not discovered during development.

Testnets function as a crucial safety net in this scenario. They allow developers to uncover and rectify any errors before the feature is publicly available.

To ensure proper functionality and safeguard the stability of the mainnet, developers often explore various security configurations during the testing process.

Meanwhile, testnets are not only accessible to developers. Invitations can also be extended to members of the public to evaluate the new features before they are launched in the open market.

This practice is a means to gather constructive feedback and collect valuable data on how end users utilize these innovative offerings.

These users are often given testnet coins to run in-depth tests on the network. These coins are often virtual and don’t require real money.

Once a feature is considered safe and all potential risks have been thoroughly addressed on the testnet, it is introduced to the mainnet.

However, these features are often proposed in the blockchain community and may not be immediately adopted. Community members are usually allowed to vote on whether to add or discard these proposed features.

Features of a Testnet

Although a testnet is quite similar in operation and use cases to the public mainnet, it comes with its features.

  • It offers a separate cryptocurrency – paper funds of the same digital asset offered in the mainnet. These testnet coins can only be used in the sandbox environment and are commonly distributed to a specific group of testers, not just developers, to thoroughly assess the complete functionality. Consequently, transactions involving testnet cryptocurrencies remain isolated and don’t impact the mainnet blockchain in any way.
  • Developers often create genesis blocks on testnets that only function within the test environment. It is similar to the mainnet in appearance, but it isn’t live. This genesis block contains specific markers and indicates the number of coins generated. As a result, it becomes impossible to transfer testnet coins to the live blockchain or to receive digital assets from external sources. This clear distinction ensures that the development and operational blockchains remain separate entities.
  • Lastly, the coin minting process on a testnet is often easier than the active blockchain. This is largely driven by the fact that the coins are meant for testing, and users will need ample quantities to get the needed data for further development. As such, blocks are mined faster, and test transactions are confirmed quicker.

How Do Testnets Work?

The surface operation of a testnet often looks like the active blockchain. Under the hood, the development team:

  • Upload features or updates on the testnet to analyze their performance.
  • During this analytical window, they check for errors in the codebase. This is usually called debugging in development circles.
  • After the debugging, the code is launched in a “sandbox,” which is a contained environment. This process allows them to test configurations and view how the features would operate on the mainnet.
  • If the feature/update is riddled with errors or the primary purpose for its development is not achieved, the team addresses all the issues discovered during this testing process.
  • On the other hand, if the update passes all the vulnerability and security tests, it is submitted for consideration to the community supporting the main blockchain.

Popular Examples of Testnets

Almost all major blockchain networks (base-layer protocols) have or had a testnet for battle-testing the network. Below are some of the most popular development hotbeds in the blockchain ecosystems.

These testnets are operational on the Ethereum network.

Sepolia Testnet

  • This was introduced in 2021.
  • Initially based on a proof-of-authority (PoA) protocol, Sepolia underwent a significant transformation when the Ropsten testnet reached a terminal total difficulty (TTD) of 5,000,000,000,000.
  • At that point, it transitioned to a proof-of-stake (PoS) consensus algorithm. This allowed it to mimic the active Ethereum blockchain, which also transitioned at that TTD height.
  • The Sepolia testnet focuses on emulating hashing network conditions and operates with shorter block times. This enables it to validate transactions more swiftly than the core Ethereum blockchain protocol, providing developers with timely feedback when needed.

Ropsten Testnet

  • Ropsten, a much older development network, was launched in November 2016.
  • It supports both Geth and Parity Ethereum node software.
  • It is the last proof-of-work (PoW) staging environment for the Ethereum protocol.
  • Ropsten provided a viable playground where developers could test highly malicious attacks on the network to evaluate its security.

One notable instance occurred in 2017 when malicious attackers inundated the Ethereum network with a high volume of complex transactions in a bid to crash it. However, the attacks were forestalled, and the necessary security was implemented.

Kovan Testnet

  • Kovan was launched in March 2017 as a backstop for Ropsten.
  • The platform operated on the same premise as its older counterpart but worked on a PoA consensus mechanism. This way, only authorized nodes are allowed to validate transactions and proceed to add new blocks.

Rinkeby Testnet

  • Rinkeby also operates as a PoW development chamber.
  • However, it uses a Geth node software and provides a simulation environment for Ethereum core developers to test new updates.

How to Use a Crypto Testnet Account?

Crypto testnets are distinctly the same in operation as their mainnet counterparts. If you’re keen on providing constructive feedback on a new testnet feature, follow these steps to become a tester:

  1. Create a Crypto Wallet: Testnets are only accessible via cryptocurrency wallets. There are varied options in the market, including Trust Wallet, Metamask, Coinbase Wallet, Exodus, and several others.
  2. Create a Testnet Address: Once the wallet is created, the next step is to create a testnet wallet address. This will be useful in receiving and storing testnet coins.
  3. Get Testnet Coins: Testnet coins are obtainable on online faucets of the respective blockchain network. Another option is to request them from the underlying network itself.
  4. Access the Testnet Network: Once the testnet coins are in the crypto wallet, it is time to use the network. To get started, head to the testnet network and connect the crypto wallet. This will enable you to send and receive coins, explore new features, and form your assessment of the network.

The Bottom Line

Testnets serve as isolated environments to try out new features or updates without compromising the main network. They provide an echo chamber where developers can easily gauge an update’s direct impact without disrupting the active blockchain’s activity.

Given this, testnets are crucial for continued blockchain ecosystem innovation.

They are also key development tools for building safe and secure Web3 applications stable enough for widespread use.


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Jimmy Aki
Crypto & Blockchain Writer
Jimmy Aki
Crypto & Blockchain Writer

A graduate of the University of Virginia, Jimmy previously worked for BeInCrypto, Bitcoin Magazine, Decrypt, Cryptonews and other major publications. Alongside writing for Techopedia, Jimmy is also a trained economist, accountant and blockchain instructor with hands-on work experience in the financial sector.