Boba Network RPC: Chain ID 288 and the Hybrid-Compute Rollup

Most rollups optimize one thing: cost. Boba Network tried to optimize the programming model too. Launched in 2021 as an EVM-compatible optimistic rollup on Ethereum, Boba (chain ID 288) is best known for Hybrid Compute — smart contracts that can trigger off-chain computation and external API calls during execution. This guide covers what you need to build on it: the chain ID, a working mainnet RPC endpoint, live fee behavior, and the usual fork-over habits.

The essentials

Boba's Ethereum L2 is chain ID 288, with:

• ETH as the gas token (the BOBA token exists as the network's governance and utility asset — not the gas currency).
• Blocks that follow transaction flow — sampled live while writing this: roughly one block every ~2 seconds, with the head past 38.5M.
• Optimistic-rollup security: fast L2 confirmations, with withdrawals to Ethereum following the ~7-day challenge window.
• A standard EVM surface — Solidity, viem, ethers, Foundry, and the usual eth_* methods.

A working config with our endpoint:

import { createPublicClient, http, defineChain } from "viem";

const boba = defineChain({
  id: 288,
  name: "Boba Network",
  nativeCurrency: { name: "Ether", symbol: "ETH", decimals: 18 },
  rpcUrls: { default: { http: ["https://rpc.swiftnodes.io/rpc/boba?key=YOUR_API_KEY"] } },
});

const client = createPublicClient({ chain: boba, transport: http() });
await client.getBlockNumber();   // just works

Hybrid Compute, from the RPC seat

The headline feature: Boba contracts can invoke off-chain compute and external APIs within a transaction — the network's Hybrid Compute framework routes those calls (including AI and Web2 data sources) and folds the results back into execution. It's a chain-level capability rather than an RPC extension, so from where you sit the interface stays boring in the best way:

• Standard eth_call / eth_estimateGas / eth_sendRawTransaction semantics apply.
• Hybrid-Compute transactions arrive through the same mempool and block flow as everything else — receipts and logs read identically.
• Indexers and dashboards need no special decoding just to follow the chain; the exotic part is what contracts choose to do with the capability.

Historically Boba shipped alongside the OMG Foundation era (BOBA was airdropped to bridged OMG holders at launch), and the network also runs deployments on other base chains such as BNB Smart Chain — chain 288 is specifically the Ethereum L2, and the one SwiftNodes serves.

Fees: milligwei country

Boba's fee numbers look like a formatting bug until you accept them. Sampled live through our endpoint while writing this:

• eth_gasPrice: ~0.001 gwei. The base fee sat several orders of magnitude below that (sub-microgwei).
• A 21,000-gas transfer therefore costs on the order of 0.00002 ETH — deep sub-cent territory.
• The sampled block was nearly empty (one transaction, ~44k gas used), which is normal for a rollup whose block production tracks demand.

Estimation flows work unchanged — eth_estimateGas and the EIP-1559 fields behave like any EVM chain (gas estimation basics apply as-is). Budget for dust, buffer as usual.

What carries over — and what to verify

• Standard reads and writes — eth_call, eth_getBalance, eth_getLogs, eth_getTransactionReceipt (receipt semantics unchanged), eth_sendRawTransaction, eth_subscribe — all behave as on any EVM chain.
• Archive access works: our block-1 state probe was answered normally, so historical queries route fine — on SwiftNodes that's &archive=1 on paid plans.
• Extension methods, verify per-method: traces and debug vary by upstream everywhere, Boba included — our weekly auto-probed matrix covers it, with the error-code reference for the responses you'll meet.
• WebSocket subscriptions fit well at this cadence (reconnection habits transfer directly).

The short version

Boba Network is chain ID 288: an EVM optimistic rollup on Ethereum with ETH gas, demand-driven blocks around 2-second pace, and fees in milligwei territory. Its signature feature — Hybrid Compute, letting contracts call off-chain compute and APIs mid-execution — leaves the RPC surface standard, so Ethereum tooling carries over as-is. Verify extension-method support per-method rather than assuming, and treat the 7-day withdrawal window as the trust horizon back to Ethereum.

Building on Boba? A flat-rate Boba Network RPC endpoint serves chain 288 over HTTP and WebSocket, load-balanced across upstreams, alongside 75+ other chains under the same key. Grab a free key and point your stack at:

https://rpc.swiftnodes.io/rpc/boba?key=YOUR_API_KEY
wss://rpc.swiftnodes.io/ws/boba?key=YOUR_API_KEY