A paymaster is a smart contract (within the ERC-4337 Account Abstraction framework) that pays gas fees on behalf of users. Instead of needing ETH for gas before you can do anything on Ethereum, a paymaster can sponsor your transaction entirely (free for you) or let you pay gas in a different token (USDC, the app own token, etc.). It removes the biggest onboarding friction in crypto: needing the native token before you can use the chain.
What Is a Paymaster (Gas Sponsorship)?
4 min read
The short version
Right now: you need ETH to do anything on Ethereum, even if you only want to move USDC. You cannot use the chain without first buying its gas token. A paymaster says: I will pay the gas for you. Maybe the app covers it (free for users, app pays for growth). Maybe you pay in USDC instead of ETH. Either way, the user never needs to think about gas tokens or manage multiple assets just to make one transaction.
How It Works
How paymasters work (ERC-4337): (1) A user creates a UserOperation (the intent to do something: swap, transfer, mint). (2) The UserOp specifies a paymaster contract address. (3) The bundler includes the UserOp in a transaction. (4) During execution, the EntryPoint contract calls the paymaster validatePaymasterUserOp() function. (5) If the paymaster approves (user meets criteria: holding the app token, is whitelisted, or payment in ERC-20 verified), it funds the gas. (6) The user transaction executes without the user spending ETH. Paymaster types: Sponsoring paymaster: app pays gas entirely (user pays nothing). Used for: onboarding new users, gasless NFT mints, free first transactions. The app budget covers gas as a growth expense. ERC-20 paymaster: user pays gas in USDC, DAI, or any token the paymaster accepts. Paymaster swaps the token for ETH internally to cover actual gas costs. User never needs to hold ETH. Verifying paymaster: user proves eligibility (holds an NFT, is on a whitelist, completed KYC) and gets sponsored gas for verified actions. Why it matters for adoption: the number one reason mainstream users abandon crypto onboarding is the gas chicken-and-egg problem (need ETH to move USDC, but cannot buy ETH without an exchange account, etc.). Paymasters eliminate this entirely. A new user can receive USDC and immediately use it without ever touching ETH.
A new user sending USDC without ever holding ETH
A freelancer receives 500 USDC from a client directly to their smart contract wallet (created via a social login, no seed phrase needed, powered by ERC-4337). They want to send 200 USDC to their landlord for rent. Traditional flow: cannot send USDC because they have 0 ETH for gas. Must create exchange account, buy ETH, wait for confirmation, then send USDC. 30+ minutes of friction. Paymaster flow: their wallet uses an ERC-20 paymaster. They click Send 200 USDC. The paymaster sees: user has USDC, charges 0.30 USDC as gas payment (converts to ETH internally). The user confirms. 200 USDC goes to landlord. 0.30 USDC goes to paymaster. User never saw, held, or thought about ETH. Their remaining balance: 299.70 USDC. Total time: 12 seconds. Zero ETH knowledge required.
What People Get Wrong
Paymasters make everything free
Someone always pays the gas (Ethereum validators still need compensation). Sponsoring paymasters mean the APP pays (from their budget, as a user acquisition cost). ERC-20 paymasters mean the USER pays but in a different token. Free for the user does not mean free for everyone; it means the cost is absorbed elsewhere in the value chain.
Paymasters only work on Ethereum mainnet
Paymasters work on any EVM chain with ERC-4337 support. They are most impactful on L2s where gas is already cheap (sponsoring $0.01 transactions is trivially cheap for apps). Deployed and active on: Ethereum, Arbitrum, Optimism, Base, Polygon, and others. The infrastructure is multi-chain.
Using a paymaster is less secure
The paymaster pays GAS, it does not control your funds. Your smart contract wallet still requires your signature to authorize any asset movement. The paymaster can refuse to pay gas (your transaction fails, no harm) but cannot redirect your funds. Security of your assets is unchanged; only who pays the execution cost differs.
Keep Reading
Sources & Further Reading
- ERC-4337 Paymasters
Registry of ERC-4337 infrastructure including paymaster providers
- Alchemy Gas Manager
Paymaster service for apps to sponsor user gas on any EVM chain
Questions People Also Ask
- How do apps afford to sponsor gas?
- On L2s (Arbitrum, Base), sponsoring a transaction costs the app $0.001-0.01. A thousand sponsored transactions costs $1-10. For apps with revenue (trading fees, subscriptions), this is negligible user acquisition cost. On Ethereum L1 (where gas is $5-20), full sponsorship is expensive and less common. Most sponsoring paymasters operate on L2s where the economics work easily.
- Can I build a paymaster for my app?
- Yes. Paymaster contracts are open-source (OpenZeppelin, Alchemy, Pimlico, and Biconomy provide templates). Deploy the contract, fund it with ETH (to cover gas), define your sponsorship rules (sponsor all users, only users holding your token, up to X transactions per day), and configure your app smart wallet to point to your paymaster address.
- Will paymasters make gas fees disappear entirely?
- For end users: effectively yes (they will not see or manage gas). For the ecosystem: no, validators still earn gas fees paid by paymasters on behalf of users. The cost shifts from user-facing to infrastructure-facing. Users get a gasless experience. Apps and paymasters handle the gas economics behind the scenes. This is the abstraction that brings crypto UX closer to web2.