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Getting Started

This high-level guide introduces how Ethera enables cross-chain transactions and composability.

How Ethera Transactions Work​

Ethera enables developers to execute transactions across multiple blockchains atomically through a single RPC call: eth_sendXTransaction.

This allows the user to bundle multiple transactions from different chains into one atomic operation. However, not all transactions can be bundled and sent via eth_sendXTransaction. Only transactions that make use of the mailbox system can be included in cross-chain bundles. Our bridge contracts use these mailbox functions and can be used directly. Custom contract integration guides are currently being refreshed.

Transaction Signing Requirements​

The eth_sendXTransaction RPC method requires signed transactions to function, as it passes raw transaction data for execution across multiple chains. While it's possible to sign transactions locally with a private key, this approach is not realistic for production dApps as it requires users to manage private keys and gas fees on each chain.

UserOperations for Production Applications​

The user experience can be improved by using UserOperations, which integrate with Account Abstraction (AA) to provide:

  • Smart Account Wallets: Advanced features like batch operations and custom validation
  • Single Signature: Sign multiple cross-chain transactions with one action
  • Paymaster usage: Developers can choose to pay the gas for certain transactions through an optional paymaster

This approach requires building and signing User Operations, which is more complex but provides a superior user experience for production applications.

Core Components​

The following is a list of important components that we deem useful, in order to obtain a good UX when developing cross-chain composable dApps:

  • Account Abstraction (AA): Smart contract–based wallet infrastructure that lets users define custom transaction logic
  • UserOperation (UserOp): ERC-4337 AA transaction data structure containing the call, gas limits, and fees
  • Kernel Account (ZeroDev, v3.1): The smart account implementation used with Ethera
  • Multi‑Chain ECDSA Validator: One validator plugin that lets the same owner control ZeroDev Kernels on multiple chains
  • Ethera Sequencer custom RPC methods:
    • compose_buildSignedUserOpsTx → turns signed UserOps into per‑chain raw txs
    • eth_sendXTransaction → submits multiple raw txs as one atomic bundle across chains

The diagram below illustrates the complete cross-chain transaction flow for composable dApps using UserOperations:

Cross-chain transaction flowCross-chain transaction flow

Next Steps​

Explore the practical implementation guides:

  • Ethera SDK: Install and configure SDK primitives for cross-chain apps
  • Execution Model: Understand how Ethera executes cross-rollup transactions, using Rollup to Rollup as the example
  • Ethera Bridge webapp: Review a complete end-to-end reference application for bridging flows across Sepolia and Ethera rollups
  • Paymaster: Configure optional sponsorship for smart-account flows
  • Tutorials: Follow step-by-step implementation examples
  • Smart Contracts: Review deployed contracts and bridge/mailbox references
  • Testnet: Configure chain IDs, RPCs, and explorer endpoints
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All linked guides assume that the target chains are already Ethera Network enabled.