If you’re coming from traditional systems, “batch transactions” sounds like a client-side feature.
In Ethereum, it’s not.
Using web3j, you’ll quickly realize that batching is not something the library (or protocol) handles natively for state-changing operations. Instead, it’s something you design around.
Let’s break down what actually works.
1. Batch RPC Calls (Read-Only)
web3j supports batching for JSON-RPC requests, which is useful for reads.
BatchRequest batch = web3j.newBatch();
batch.add(web3j.ethGetBalance(addr1, DefaultBlockParameterName.LATEST));
batch.add(web3j.ethGetBalance(addr2, DefaultBlockParameterName.LATEST));
BatchResponse response = batch.send();
When to use this:
- Dashboards
- Analytics
- Monitoring tools
Limitations:
- No state changes
- Not executed on-chain This is purely a network optimization. 2. Multicall Contracts (Real Batching) If you want to batch actual transactions, you need to move the logic on-chain. A common pattern is a multicall function:
function multicall(bytes[] calldata data) external {
for (uint i = 0; i < data.length; i++) {
(bool success, ) = address(this).delegatecall(data[i]);
require(success, "Call failed");
}
}
How it works:
- Encode multiple function calls in web3j
- Send them as a single transaction
- Contract executes them sequentially Benefits:
- Atomic execution (all succeed or all fail)
- Single transaction → better UX
- Lower overhead vs multiple txs This is how most production dApps implement batching.
3. Sequential Transactions (Fallback)
The simplest approach is just looping:
for (...) {
TransactionReceipt receipt = sendTransaction(...);
}
Downsides:
- Not atomic
- Multiple gas fees
- Slower confirmation Only useful when atomicity isn’t required.
Key Insight: Batching Is a Contract Problem
The important mental model:
Ethereum doesn’t batch transactions at the client level — it batches execution at the contract level.
web3j is just a client. It can:
- Optimize requests (RPC batching)
- Send transactions But it can’t change how the EVM executes them.
Why This Matters for Builders
If you’re designing a dApp, this decision affects:
- UX (one signature vs many)
- Gas efficiency
- Failure handling
- Composability
Multicall patterns have become standard because they align with how Ethereum actually works.
A Broader Pattern
This “bundle then execute” model shows up across crypto systems.
You see it in high-variance environments like Degenroll:
- Setup happens quietly
- Then execution happens in one decisive outcome Instead of spreading actions across time, everything resolves in a single event.
Final Takeaway
With web3j:
- Use BatchRequest → for read optimization
- Use multicall contracts → for real batching
- Avoid sequential txs when atomicity matters
Once you understand that batching lives in smart contracts — not the client — the architecture becomes much clearer.
