What is ERC-4337?

The specification that brought smart-contract wallets to Ethereum without changing the protocol, by routing intents called user operations through a shared entry-point contract.

Bundlers collect these operations and submit them as ordinary transactions, and an optional paymaster can settle the gas, which is how an application can let you transact without holding ETH (source: ERC-4337). It is the standard behind account features such as spending limits, session keys, and social recovery. The trade-off is added moving parts: bundlers, paymasters, and the wallet contract itself are all code that can fail or be misconfigured.

The practical thing to know is that a wallet built this way is a contract, not a key pair. That changes how it behaves across chains and, more immediately, how some exchanges treat it.

How it works

An ordinary Ethereum account is a private key. It can only do what the protocol allows an account to do: pay gas in ether and sign one transaction at a time. ERC-4337 replaces that account with a contract you control, and routes your intent through separate infrastructure (source: ERC-4337).

1. You sign a user operation. It describes what you want done, not a raw transaction. Your wallet contract decides what counts as a valid signature, which is where passkeys, multiple signers, and session keys become possible.
2. A bundler picks it up. Bundlers watch an alternative mempool, group operations together, and submit them as a normal transaction to a shared entry-point contract.
3. The entry point validates and executes. It asks your wallet contract to approve the operation, then runs it, then settles payment.
4. A paymaster may pay the gas. An application or a sponsor can cover the fee, or accept payment in a token instead of ether.

The features people actually want follow from step one. Because your contract defines validity, it can enforce daily limits, require a second signer above a threshold, allow a game to act within a bounded session, or let trusted parties help you recover access. See account abstraction and social recovery.

The cost is complexity. Deploying the wallet costs gas, the contract exists separately on each chain, and the address is not guaranteed to be identical everywhere.

Example

Illustrative flow. You buy a token on an application that sponsors gas. You sign a user operation approving a swap; a bundler includes it; a paymaster pays the illustrative $0.40 network fee and charges you the equivalent in the stablecoin you were already holding. You never held ether, and the swap settled in one step rather than the usual approve-then-swap pair.

Why it matters when you buy

Some exchanges reject withdrawals to contract addresses, or credit deposits from them unpredictably, so a smart-contract wallet is not always a drop-in replacement for a standard address. Test with a small amount before moving a full balance, and check a venue's withdrawal rules at the exchange pages.

Related terms

account abstraction — the capability this delivers, paymaster — who can pay your gas, smart contract — what the wallet actually is, social recovery — regaining access without a seed phrase, passkey — a common signing method, gas — the cost being abstracted away.

Questions

Do I still need a seed phrase?

Not necessarily. A contract wallet can be controlled by a passkey, several signers, or a recovery set, which removes the single phrase as the only key. It also means the wallet's own rules determine recovery, so read them before relying on it.

Can I withdraw from an exchange straight to a smart-contract wallet?

Sometimes. Policies vary and some venues block contract addresses outright. Send a small test amount first and confirm it arrives before moving anything substantial.

Is gasless really free?

No. Someone pays, usually the application through a paymaster, and often by charging you in a token instead. Free to you is not the same as free.