Bundler
A bundler is the permissionless worker of ERC-4337 account abstraction: it collects user operations from the mempool, bundles them into one on-chain transa
A bundler is the permissionless worker of ERC-4337 account abstraction: it collects user operations from the mempool, bundles them into one on-chain transaction, and earns fees for the service. Anyone can run one — no license, no staking requirement.
How it works
Users sign intents instead of raw transactions; bundlers package compatible operations (checking each wallet’s validation logic and paymaster sponsorship), submit the bundle, and get paid from per-operation fees. Competition between bundlers sets the market price for inclusion.
Why it matters for decentralization
Bundlers replace the centralized relayers of old meta-transactions with an open market — the design only stays censorship-resistant if many independent bundlers actually operate. Watch bundler concentration the way you watch mining pools: whoever packages transactions can delay or exclude them.
Risks & trade-offs
Early centralization (a few professional bundlers dominate); reputation/spam dynamics in the alternative mempool; and UX dependence — if bundlers vanish, smart wallets stall even though funds stay safe.
FAQ
Do I choose a bundler? Your wallet does, automatically — picking by fee and reliability, like gas price selection today.
Can a bundler steal my funds? No — it can only include your pre-signed operation or ignore it. Censorship, not theft, is the risk.
Why not just use normal transactions? Smart wallets *can’t* — their logic needs the ERC-4337 flow. Bundlers are the price of programmable accounts.
Related terms
ERC-4337 ·
account abstraction · paymaster