What Is a Testnet?
A testnet is a version of a blockchain that runs on tokens with no real value. Developers use it to test smart contracts and network upgrades before mainnet, and users can try new apps without risking money.
On this page 6
A testnet is a version of a blockchain that runs on tokens with no real value. It mirrors the rules and behavior of the mainnet, but the coins on it can’t be sold for anything. Developers use testnets to try out smart contracts, wallet integrations and protocol upgrades without putting real money at risk.
What is a testnet used for?
- App development: developers deploy and debug smart contracts on a testnet before going live.
- Network upgrades: major protocol changes are activated on testnets first. Ethereum’s switch to proof of stake, The Merge, was rehearsed on several testnets before mainnet.
- User practice: people can learn a new app’s workflow without losing money.
- Infrastructure checks: exchanges and wallet providers test integrations before supporting a new network.
Well-known testnets
Ethereum: Sepolia is the main recommended testnet for application developers, while Hoodi, launched in 2025, is aimed mainly at validator and infrastructure testing. Older testnets such as Ropsten, Rinkeby and Goerli have been retired over time, a good reminder that testnets are not permanent. Layer 2 networks run their own test versions too; Arbitrum and Optimism, for example, both offer testnets built on Sepolia.
Bitcoin: Bitcoin has several test environments. Testnet4 began replacing the long-running testnet3 in 2024. Signet offers a more predictable environment because its blocks are signed by designated parties, and regtest is a private network developers spin up on their own machine. Bitcoin testnet addresses typically start with “tb1,” which makes them easy to tell apart from mainnet addresses.
What is a faucet, and how do you get test tokens?
A faucet is a service that hands out small amounts of free test tokens so you can pay transaction fees on a testnet. The usual steps are:
- Enable test networks in your wallet and select the right one.
- Copy your address and paste it into a reputable faucet.
- Expect some limits: to stop abuse, faucets may impose waiting periods, ask you to verify a social account or require a small mainnet balance.
A faucet has no reason to ask for your recovery phrase or private key. Any request like that is a scam.
What should you watch out for on a testnet?
Test tokens are worthless; multiplying them by the price of the mainnet asset with the same name tells you nothing. Testnets can be reset or shut down, and their data can disappear.
Some projects run “incentivized testnets” and say active testers may be rewarded later. Unless the project has officially announced such a distribution, don’t treat testnet activity as a guaranteed airdrop. Using a separate wallet that holds none of your real assets also reduces the chance of transacting with real funds by mistake.
An app running smoothly on a testnet doesn’t prove it’s safe on mainnet. Real liquidity, heavy traffic and attackers’ financial incentives can’t be fully reproduced in a test environment.
Frequently asked questions
Can testnet tokens be sold?
They are designed to be worthless and aren’t listed on exchanges. Offers to sell you test tokens are usually scams.
What’s the difference between a testnet and a devnet?
A devnet is usually a short-lived, more closed network set up by development teams for early experiments. A testnet is open to a wider community and serves as a closer rehearsal for mainnet.