What Is a Testnet? Practice Minting NFTs for Free

What a Testnet Actually Is

A testnet is a separate copy of a blockchain network that behaves almost exactly like the real one, except the tokens on it have no real value. Ethereum, for example, has a live “mainnet” where transactions cost real ETH and every mint is permanent and public. It also has testnets, such as Sepolia, that mirror the same rules and the same wallet software, but run on tokens that anyone can get for free.

For someone learning how to mint an NFT, this matters a lot. You can connect a wallet, approve a transaction, watch it confirm, and see the resulting token show up in your wallet, all without touching your own funds. If something goes wrong, the only thing you lose is a bit of time.

Why Practice Before You Mint for Real

Minting on mainnet is not reversible. Once a transaction is confirmed, you cannot undo it, and gas fees are paid whether the mint succeeds the way you expected or not. New NFT creators often run into a handful of avoidable mistakes on their first real mint:

• Approving a transaction without reading what it actually authorizes.
• Uploading artwork in a file format the marketplace does not display correctly.
• Confusing which network their wallet is connected to before confirming.
• Underestimating gas costs and having a transaction fail partway through.

A testnet lets you make every one of these mistakes without financial consequences. You can mint a test collection, check how it renders on a marketplace or in your wallet, and only move to mainnet once the whole process feels familiar.

Testnets You Will Run Into

Different networks maintain their own testnets, and the names change over time as older ones are retired. As of 2026, a few you are likely to encounter when minting NFTs are:

• Sepolia, the testnet most commonly recommended for Ethereum application testing. It uses a free token, also called Sepolia ETH, that has no market value.
• Base Sepolia, the testnet for Base, the Ethereum layer 2 network built by Coinbase. It also settles against Sepolia and uses ETH as its test currency.
• Polygon Amoy, the current testnet for Polygon PoS, which replaced the older Mumbai testnet. It uses a free token called POL for gas.

If you plan to mint on a specific chain, look for that chain’s testnet by name rather than assuming one testnet works everywhere. Testnets are tied to the same network family as their mainnet counterpart, so a Polygon testnet will not let you practice an Ethereum mainnet mint.

Getting Free Testnet Tokens

You get testnet tokens from a faucet, a website that sends a small amount of test currency to a wallet address for free. Faucets exist for most major testnets and are usually run by infrastructure providers, wallet companies, or the blockchain team itself. Typical faucet limits are small, often a fraction of a token per day, but that is more than enough to cover several test mints since testnet gas costs nothing in real terms.

To use one, you generally need a wallet address and, on some faucets, a small amount of real mainnet ETH already in a linked account to prove you are not a bot. Once the tokens land in your wallet, make sure your wallet app is switched to the matching testnet before you try to mint. Sending a transaction on the wrong network, or trying to mint with mainnet selected when you meant to test, is one of the most common points of confusion for beginners.

What Testnet Minting Can and Cannot Teach You

Testnets are excellent for learning the mechanics: connecting a wallet, reviewing a transaction, understanding what metadata gets attached to your token, and seeing how an image or file renders once it is minted. They are also useful for testing a whole collection workflow before a real drop, including checking that a reveal step or a batch of files behaves the way you expect.

What they cannot teach you is anything about market value, since testnet tokens have no buyers and no price discovery. They also will not fully reflect mainnet congestion, since gas costs and confirmation times on a busy mainnet can differ from a quiet testnet. Treat a testnet as a rehearsal for the technical steps, not as a preview of demand for your work.

Moving From Testnet to Mainnet

Once a test mint has gone smoothly, moving to mainnet is mostly a matter of switching your wallet’s network back, funding it with real ETH or whatever currency your target chain uses, and repeating the same steps. Double check the contract address and network one more time before confirming, since a real mint carries a real gas fee and cannot be reversed.

If you are using a mobile app like Simple NFT Creator to mint your first collection, you can go through this same testnet rehearsal from your phone before switching to a real network, so your first mainnet mint is not also your first time going through the process. Simple NFT Creator is available on the App Store and Google Play.