If you've been practicing good wallet hygiene on Revoke.cash, you might have noticed tokenapprovals on networks you don't recognize. Ever heard of Sepolia, Goerli or Mumbai?
This often leads to the burning question "If I approve a transaction on a testnet, can a scammer jump over to my mainnet wallet and steal my real ETH?" The short answer: No. But there are a few nuances every Web3 user should understand.
What Are Testnets?
Testnets are sandboxed versions of blockchains like Ethereum, Polygon or Arbitrum. Developers use them to test smart contracts and applications before deploying them to the real network (mainnet).
Think of a testnet like a driving simulator. You can use the steering wheel, the pedals and even crash the car - without any real-world consequences.
Testnet tokens (like Sepolia ETH) are free and have no market value
Mainnet tokens (like ETH or USDC) are real assets with real value
Why Testnet Approvals Stay on Testnets
Each blockchain network is cryptographically isolated through a mechanism called chain IDs. When you sign any transaction, whether it's an approval, transfer or Permit signature, your wallet automatically includes the chain ID in the cryptographic signature itself.
This means:
A transaction (like an approval) signed for Sepolia (chain ID 11155111) is mathematically invalid on Ethereum Mainnet (chain ID 1)
The blockchain will reject any attempt to replay a testnet transaction on mainnet
This protection happens at the protocol level, before any smart contract code even executes
Additionally, when you deploy the same smart contract to both testnet and mainnet, they become two completely separate instances with different addresses and independent storage. An approval on the testnet version has no connection to the mainnet version.
Do You Need Revoke Testnet Approvals?
Leaving an approval active on a testnet does not put your real funds at risk. However, at Revoke.cash we believe in overall wallet hygiene. Cleaning up testnet approvals is a great way to practice revoking approvals without spending real gas fees.
TL;DR
Testnet approvals are safe and do not affect your mainnet tokens
Testnet tokens are free and have no market value
Scammers use fake testnet airdrops and phishing sites to trick you into giving real mainnet approvals or revealing your seed phrase
Always verify which network your wallet is connected to before signing any transaction
FAQ
No. While Permit signatures are signed off-chain, they are still tied to a specific chain ID. A signature intended for a testnet will be rejected by smart contracts on mainnet.
We support over 100 networks, including testnets, because we are a tool for everyone. Developers rely on Revoke.cash during the build phase to verify that their smart contracts request and clear permissions correctly before going live.
No. You likely interacted with a faucet or a dApp that distributed test tokens. Since these tokens have no value, scammers have no incentive to steal them. They are just part of the testing ecosystem.
In most cases, no. Modern wallets (like MetaMask or Rabby) will warn you if you are trying to send assets to an incompatible network. Always double-check your network selector at the top of your wallet before signing or sending any transaction.
No. Scammers often airdrop testnet tokens and create fake price feeds that show inflated values. These tokens have zero real-world value and cannot be sold on legitimate exchanges. This is a social engineering tactic to lure you to phishing sites. If testnet tokens show a price, it's fabricated. Legitimate testnet tokens explicitly display as worthless.
While using the same address is technically safe, many developers prefer using separate wallets for testnet and mainnet. This reduces confusion about which network you're on and makes it harder for scammers to use social engineering tactics. If someone shows you "your address" with testnet activity and claims it affects your mainnet funds, using separate addresses makes the scam obvious.
Yes, if you manually add a custom RPC endpoint to your wallet. Always verify that both the RPC URL and the chain ID match your intended network (for example, Ethereum Mainnet = chain ID 1). If you add a mainnet RPC but accidently set it with a testnet chain ID, your wallet may display incorrect information. Only use official RPC endpoints from trusted sources and double-check the network name displayed in your wallet matches the network where you intend to transact.
