EIP-4337: Account Abstraction Using Alt Mempool
EIP-4337 is the deployed standard powering smart wallets across Base, Optimism, Arbitrum, and Polygon (Coinbase Smart Wallet, Safe{Core}, Biconomy, Pimlico, Alchemy AA). Required knowledge for building AI agents that pay gas through Paymasters, gasless onboarding flows, and any wallet experience that doesn't start with "buy ETH first."
What It Defines
Implements account abstraction without consensus-layer changes by introducing a higher-level UserOperation pseudo-transaction, an alternate mempool, a singleton EntryPoint contract, and Bundler nodes that pack UserOps into regular transactions. Enables smart contract wallets with arbitrary signature schemes (passkeys, multisig, social recovery), gas sponsorship via Paymasters, batched calls, and session keys — all without the user ever holding an EOA.
Canonical (Normative)
Convenient (Practical)
Related References
The Ethereum community's open process for proposing changes to the protocol. EIPs cover core protocol changes; ERCs (Ethereum Request for Comments) cover application-layer standards like token interfaces.
Related Specs
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x402 is the leading candidate for the agent-economy payment rail: it lets an AI agent (or any HTTP client) pay for an API call inline, with no API key, no signup, and no human-in-the-loop. If you're building agentic apps, paid MCP servers, per-request data products, or anything where "charge for this request without a session" matters, x402 is the standard to know — supported by Coinbase, Cloudflare, Vercel AI Gateway, and a growing facilitator ecosystem.
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