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Glossary · Wallets

What is ERC-20?

ERC-20 is the standard interface for fungible tokens on Ethereum and other EVM chains. It defines how balances, transfers and approvals work.

How does an ERC-20 token work?

Fabian Vogelsteller proposed it on GitHub on November 19, 2015, and the final EIP-20 lists him and Vitalik Buterin as authors. It has been the template for nearly every fungible token on Ethereum since. The interface is tiny: six required functions, among them balanceOf, transfer, approve and transferFrom, plus two events that wallets and explorers listen for. Implement those and any EVM wallet can hold the token and anyone can open a pool for it on an EVM DEX.

Each ERC-20 token is its own contract at its own address. USDC on Base and USDC on Arbitrum are different contracts, and anyone can deploy a fake called USDC, so the contract address matters more than the ticker. The standard also leaves room for extras the name does not warn you about: transfer taxes, blacklists, a pause switch, an owner who can mint more. Reading the contract, or a trusted audit of it, shows which of those powers exist.

The approve and transferFrom pair is how DEXs and lending markets move your tokens for you. It is also where attackers aim. Revoking old approvals is boring. Do it anyway.

If you approve a DEX router for exactly 1,000 USDC, it swaps the 1,000 and the allowance drops to zero. Approve unlimited instead and the router keeps the right to move your USDC long after the swap.

Also called: ERC20, ERC-20 token, EIP-20.

Where does ERC-20 show up in Cashboard?

Watch-only EVM portfolios read the native coin and ERC-20 balances of a public 0x address through Blockscout, and a token Blockscout cannot price shows n/a and stays out of the total. Cashboard never asks for a token approval, so there is no Cashboard approval to revoke.

Frequently asked questions

Why do I need ETH to send an ERC-20 token?

Moving any token is a transaction, and transactions pay gas in the chain's native coin. On Ethereum, Base and Arbitrum that coin is ETH, so a plain wallet holding only USDC usually cannot send it until it gets a little ETH, unless the wallet or app covers the gas for you.

Where can you read more about ERC-20?

Related terms

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