What Is ERC-4337? Account Abstraction and Gas in Any Token

ERC-4337 is the Ethereum standard that brings account abstraction to EVM chains without changing the protocol itself: instead of an address controlled by one private key, your wallet becomes a smart contract that decides in code who may authorise a transaction and which token pays the fee. It runs on a parallel “alt-mempool” — you sign a UserOperation rather than a raw transaction, a bundler packs several of them into one ordinary on-chain transaction, a single shared EntryPoint contract validates and executes them, and an optional paymaster can sponsor the gas outright or accept an ERC-20 token in place of native gas. That is what unlocks paying fees in a token you already hold, gasless onboarding, batching approve-and-swap into one atomic step, scoped session keys and social recovery. It is EVM-only: Solana and TON reach comparable outcomes through their own separate-fee-payer and relayer designs, not through ERC-4337. WATS is one concrete implementation — the non-custodial WATS Hot Wallet uses an ERC-4337 paymaster on its EVM chains so network fees are charged in a single token, ATS, instead of each chain’s native gas token.

The problem: EOAs and the pain of native gas

Every ordinary Ethereum wallet is an externally owned account (EOA): an address controlled by a single private key. EOAs are simple, but they are also rigid. They can only be triggered by that one key, they can only execute one call at a time, and — critically — they can only pay transaction fees in the chain's native token. To move a stablecoin on Ethereum you still need ETH for gas. To do the same on a rollup you need that rollup's native asset. The result is a familiar new-user trap: your funds are in one token, but the network refuses to act until you also hold a different one.

Beyond gas, EOAs offer no built-in recovery. Lose the key and the account is gone forever. There is no way to batch an approve-and-swap into a single atomic step, no way to delegate a narrow permission to a game or dapp, and no way for a third party to sponsor your fees. For years these limits were treated as facts of life, because changing them seemed to require changing Ethereum itself.

What ERC-4337 actually is

ERC-4337 is the standard that delivers account abstraction without touching the consensus layer. Instead of a hard fork that redefines how accounts work at the protocol level, it introduces a higher-level system that lives entirely in smart contracts and off-chain infrastructure. Accounts become programmable smart contracts, and the logic that validates a transaction — who may sign it, in what token fees are paid, what limits apply — is written in code you control rather than hardwired into the base protocol.

The mechanism is a second, parallel alt-mempool. Regular transactions flow through Ethereum's normal mempool; ERC-4337 intents flow through their own. Because none of this required a protocol change, ERC-4337 shipped as an application-layer standard and has been live on Ethereum mainnet since 2023, then across most major EVM rollups. That is its defining trick: real account abstraction, retrofitted onto an unchanged blockchain.

The core pieces

Four moving parts make it work. A UserOperation is the ERC-4337 equivalent of a transaction — a structured object describing what the account wants to do, which you sign and drop into the alt-mempool. A Bundler is an off-chain actor that collects these UserOperations, packages several together, and submits them on-chain as a single ordinary transaction, paying the actual ETH gas up front. The EntryPoint is one canonical, audited smart contract that every bundle passes through; it verifies each operation and invokes the target smart account, acting as the trusted choreographer for the whole flow.

The fourth piece is the Paymaster: an optional contract that agrees to cover gas for a UserOperation, either sponsoring it outright or accepting payment in an ERC-20 token instead of ETH. The paymaster is where most of the user-facing magic originates, and it deserves its own treatment — see what a paymaster is for the full picture.

What it unlocks

Once fee logic and validation are programmable, a lot becomes possible. Paying gas in any token is the headline: a paymaster can let you settle fees in a stablecoin or a project token while it handles the ETH behind the scenes — the core idea behind gas abstraction. Sponsored or gasless transactions let an app pay fees for its users, smoothing onboarding. Batching collapses multi-step flows — approve then swap — into one atomic UserOperation. Session keys grant a dapp a scoped, time-limited permission so you are not signing every single action. And social recovery replaces the single fragile private key with policies like multi-signer approval or trusted guardians, so a lost device no longer means lost funds.

Scope: ERC-4337 is EVM-only

It is worth being precise about reach. ERC-4337 is an Ethereum standard built around the EVM, the EntryPoint contract, and the alt-mempool. It runs on Ethereum and EVM-compatible chains — not on non-EVM networks. Solana and TON never had EOAs in the same sense and do not use ERC-4337 at all; instead they achieve comparable outcomes through their own designs. On Solana a fee-payer can be named separately from the transaction's signer, so a relayer can cover fees. TON uses a smart-contract-wallet model with relayers that can pay on a user's behalf. The user-facing effect — someone else's infrastructure fronts the native fee — rhymes with a paymaster, but the plumbing is entirely different. ERC-4337 itself does not execute on Solana or TON.

Status and limits as of 2026

As of 2026 ERC-4337 is mature and widely deployed, with a shared EntryPoint and a growing bundler and paymaster ecosystem. The main frictions are structural: smart accounts cost more gas to deploy and operate than bare EOAs, the bundler layer adds infrastructure to run or rely on, and support is uneven across tooling. A complementary track, EIP-7702, adds protocol-level support letting existing EOAs temporarily adopt smart-account behavior, narrowing the gap between the two models. Expect the two approaches to coexist and converge rather than one simply replacing the other.

How WATS uses ERC-4337

ERC-4337 is a standard, not a product — what matters is what a wallet builds on top of it. In the WATS Hot Wallet, every action — transfers, swaps, staking — is charged in a single token, ATS, instead of the chain’s native gas token. On EVM chains that is done with an ERC-4337 paymaster: the paymaster settles the real native fee on-chain while your balance is debited in ATS. It is not a discount — the network still charges its true cost and still gets paid, so ATS changes which token settles the fee, not what the transaction costs. None of this touches custody: WATS is fully non-custodial, you hold the keys, and WATS never holds a key. Because ATS is a LayerZero OFT rather than a set of wrapped copies, one balance covers fees across the EVM chains WATS supports — Ethereum, Arbitrum, Optimism, Base, Polygon and BNB Chain — as well as Solana and TON, where the same single-token experience comes from those chains’ own fee-payer and relayer mechanisms rather than from ERC-4337. The ATS collected as fees is burned, taking total supply from 100,000,000 toward a 30,000,000 floor. That combination — ERC-4337 paymaster fees plus a LayerZero OFT fee token and a supply burn — is what makes WATS the first and only wallet of its kind. If you want to see account abstraction as a user experience rather than as a spec, the practical next step is to send a transfer from the WATS Hot Wallet on an EVM chain and watch the fee come out of your ATS balance instead of ETH; the full mechanics are on the ATS fee page.