Track 6 · dApps & frontend · lesson 9

Getting a wallet and testnet ETH

10 min

To touch a real network you need two things you have so far done without: a wallet holding a key, and some ETH to pay gas. On a testnet, both are free — and the key still matters.

The wallet

Install a browser wallet — MetaMask, Rabby, or Frame. On first run it generates a seed phrase. Everything from track 2 applies now for real:

Write the phrase on paper, not in a screenshot or a synced note.
This wallet is for testnet and learning. Keep real funds elsewhere.
Nobody will ever legitimately ask you for the phrase.

Make a dedicated development wallet and never put meaningful money in it. You will paste its address into faucets, connect it to half-built contracts, and sign things while experimenting. A burner you would not mind losing is exactly the right tool for that.

Testnet ETH

Sepolia is Ethereum's main testnet. Its ETH is worthless and free, from a faucet: paste your address, pass a light anti-bot check, receive a small amount minutes later.

Faucets are often rate-limited or gated behind a mainnet-balance check, because free things get abused. If one is dry, there are several; the ecosystem keeps a current list.

Predict

Testnet ETH is free and worthless. So does the private key protecting it matter?

Yes — the habits you build here are the ones you'll use with real fundsNo — worthless funds mean the key is irrelevantOnly if you plan to go to mainnet

The RPC endpoint

To send transactions you also need an RPC endpoint for Sepolia — a node to broadcast through. Free tiers from Alchemy or Infura are plenty; you sign up, create an app, and copy the URL. Your wallet has default endpoints too, but your own deploy scripts will want their own.

Keep that URL and any API key in a .env file, never committed to git. Leaked keys get abused within minutes.

Check

What is the right kind of wallet for learning and testnet work?

A dedicated burner wallet with no real fundsYour main wallet, so everything is in one placeA hardware wallet, for maximum security

Worth remembering

You need a wallet and gas to touch a real network; on testnet both are free.
Use a dedicated burner wallet and never put real funds in it.
Sepolia is the main Ethereum testnet; get worthless ETH from a faucet.
Testnet key habits are the habits you'll use with real money — practise them now.
Keep RPC URLs and API keys in an uncommitted .env; leaked keys get abused fast.