Engine v2.1.0: Smart Backend Wallets

Prithvish Baidya

Engine v2.1.0 introduces Smart Backend Wallets, powered by account abstraction. Key benefits include:

• No more gas management
• No need to hold crypto
• Fewer stuck transactions
• Backward-compatible interface
• One-step setup

Smart backend wallets send all transactions as user operations from a smart wallet using thirdweb's paymaster. Your wallets no longer need to hold or top-up gas funds, and thirdweb sends you a bill for your gas used.

No more top-ups also means your business no longer needs to hold crypto. This is great news for any business that must avoid holding cryptocurrency tokens for regulatory or financial reasons.

Use a smart backend wallet with an AWS KMS or GCP KMS wallet for enterprise-grade security for the signer.

While Engine v2 processes transactions very fast, some chains or nodes may throttle transactions submitted from a single backend wallet. Smart backend wallets circumvent this limitation because transactions (or "user operations") are sent from a large fleet of bundler wallet addresses.

Smart backend wallets behave like existing (EOA) backend wallets. Simply update your app's x-backend-wallet-address header with the smart backend wallet address. All of Engine's endpoints are supported.

Engine creates an EOA signer wallet and deploys a smart account using thirdweb's battle-tested account factory, or your own.

The EOA signer wallet may be a local wallet, AWS KMS, or GCP KMS. You don't need to keep track of this wallet, Engine manages it behind the scenes.

The thirdweb account that deployed Engine (cloud-hosted) or tied to the thirdweb secret key (self-hosted) will be billed for gas usage. A valid payment method must be on file to send transactions on mainnet chains.

Smart backend wallets are enabled on all Engine tiers (Standard, Premium, Enterprise, and self-hosted) for no added cost.

User operations on testnet are free, and thirdweb charges a 10% fee for gas used on mainnet chains. See Pricing for more details.

See the list of chains that support account abstraction on thirdweb. Don't see your chain? Reach out to us!

The existing Create Backend Wallet endpoint now supports new types: smart:local, smart:aws-kms, and smart:gcp-kms:

POST /backend-wallet/create
{
    "type": "smart:local"  // or smart:aws-kms, smart:gcp-kms
}

(Dashboard support coming soon.)

Now provide the backend wallet address to any Engine API that accepts a backend wallet to start using it. We can't wait to see what you build with these new capabilities!

This update represents a major step forward in making web3 infrastructure more accessible and manageable for teams. Whether you're building a game, marketplace, or DeFi app, smart backend wallets provide the foundation for scalable, secure, and efficient blockchain operations.

The benefits mentioned above address the top pain points we heard from customers, and we believe account abstraction-based wallets are the ideal solution.

Account abstraction is complex, but thirdweb (Engine, SDK, infrastructure, contracts) handles the full stack:

• Manage smart accounts
  • Deploy and manage smart account factory contracts
  • Initialize EntryPoint contract connections
  • Handle complex account deployment logic
  • Manage deterministic address computation
• Send user operations
  • Build UserOperation
  • Calculate gas parameters (verification gas, pre-verification gas)
  • Handle signature schemes and validation
  • Manage nonces across operations
• Bundler infrastructure
  • Run or connect to ERC-4337 bundlers
  • Handle bundler connections and failovers
  • Monitor bundle status and handle failures
  • Manage complex retry mechanisms
• Gas management
  • Maintain gas balance
  • Alert and top-up wallets
  • Handle gas price fluctuations
  • Manage paymaster integrations

The small team at thirdweb is on a mission to build the most intuitive and complete web3 platform. Our products empower over 70,000 developers each month including Shopify, AWS, Coinbase, Rarible, Animoca Brands, and InfiniGods.

See our open roles. We’d love to work with you!