How do you get an Ethereum RPC endpoint for a fintech app?

A fintech app that touches Ethereum needs one thing before anything else works: a reliable RPC endpoint. It is the HTTP or WebSocket address your backend calls to read balances, estimate gas, broadcast signed transfers, and watch for confirmations. The endpoint you pick in a prototype is rarely the one you should run in production, because payment flows fail in ways that a demo never exposes.

This page covers how to obtain an endpoint, the exact chain settings you need, a quick way to verify it works, and the criteria that separate a development endpoint from one you can put behind a money movement service.

Which endpoint type fits your fintech workload?

Before you copy a URL, decide what kind of endpoint matches your traffic and risk profile. Most fintech teams move through these tiers as they grow.

If you are still validating an idea, a public endpoint is fine. The moment real customer balances or settlement timing depend on the response, move to a managed RPC API such as OnFinality's Ethereum RPC API, and consider a dedicated node when you need isolated capacity or stricter control over the environment.

Ethereum chain settings you must configure

Ethereum mainnet has fixed values. Getting these wrong is the most common reason a wallet or backend fails to connect.

For a wallet-style network config, the shape looks like this:

{
  "chainId": "0x1",
  "chainName": "Ethereum Mainnet",
  "nativeCurrency": { "name": "Ether", "symbol": "ETH", "decimals": 18 },
  "rpcUrls": ["https://eth.api.onfinality.io/public"],
  "blockExplorerUrls": ["https://etherscan.io"]
}

Note that chain IDs in wallet configs are hex-encoded. 0x1 is chain ID 1. If your backend uses a decimal chain ID, keep it as 1 and convert only at the wallet boundary.

Get an endpoint and verify it in one call

The fastest way to confirm an endpoint is live is a single JSON-RPC request. eth_chainId returns the chain ID and proves the endpoint is answering.

curl -s https://eth.api.onfinality.io/public \
  -H "Content-Type: application/json" \
  -d '{"jsonrpc":"2.0","id":1,"method":"eth_chainId","params":[]}'

A healthy response looks like:

{"jsonrpc":"2.0","id":1,"result":"0x1"}

If you get 0x1, the endpoint is reachable and on mainnet. From there, check the methods your app actually depends on. For a fintech app, that usually means eth_getBalance, eth_getTransactionCount, eth_estimateGas, eth_sendRawTransaction, and eth_getTransactionReceipt.

In JavaScript with viem, a minimal read looks like this:

import { createPublicClient, http } from 'viem';
import { mainnet } from 'viem/chains';

const client = createPublicClient({
  chain: mainnet,
  transport: http('https://eth.api.onfinality.io/public'),
});

const balance = await client.getBalance({
  address: '0x0000000000000000000000000000000000000000',
});
console.log(balance);

Run these checks against every candidate endpoint before you commit. It takes minutes and prevents a class of production incidents.

Production readiness checklist

A working endpoint is not the same as a production-ready one. For a fintech app, evaluate these before you route real value through it.

• Archive access. If you reconcile historical balances or backfill ledgers, confirm the endpoint serves archive data. A non-archive node will fail on older block queries.
• Trace and debug methods. Reconciliation and internal transfer tracking often need debug_traceTransaction or trace_* methods. Confirm they are enabled.
• WebSocket support. Confirmation monitoring is cheaper over subscriptions than polling. Check that eth_subscribe works if you plan to use it.
• Throughput and burst behavior. Payment batches create spikes. Understand how the endpoint handles bursts rather than only average load.
• Failover. Never depend on a single URL. Configure a secondary endpoint and a health check that switches on failure.
• Observability. You need per-method latency, error rates, and a way to tell an endpoint problem from an application bug.

If you want a structured way to compare providers against these criteria, see how to choose an RPC provider.

Monitoring confirmations without hammering the endpoint

Fintech apps care about finality, not just submission. Polling eth_getTransactionReceipt in a tight loop wastes capacity and adds latency jitter. A WebSocket subscription is usually a better fit for confirmation tracking.

const ws = new WebSocket('wss://eth.api.onfinality.io/public');

ws.onopen = () => {
  ws.send(JSON.stringify({
    jsonrpc: '2.0',
    id: 1,
    method: 'eth_subscribe',
    params: ['newHeads'],
  }));
};

ws.onmessage = (event) => {
  const msg = JSON.parse(event.data);
  // Track block height and match against pending transactions
  console.log(msg);
};

Pair subscriptions with a fallback poll at a sensible interval. If the socket drops, you should still detect confirmations rather than silently stalling a settlement.

Common failure modes and how to debug them

Most endpoint problems show up as a small set of symptoms. Match the symptom to the likely cause before you escalate.

Nonce handling deserves special attention in fintech systems because multiple services may sign from the same address. If you see nonce too low or replacement transaction underpriced, the issue is usually application-side sequencing, not the endpoint.

Where OnFinality fits

OnFinality provides RPC API access and dedicated node infrastructure across many networks, including Ethereum. You can use the public endpoint for early testing and move to a managed or dedicated setup as traffic and compliance needs grow. Because the same platform covers multiple chains, a fintech app that later adds settlement on another network can keep a consistent operational model rather than stitching together separate providers.

Review RPC pricing to match a plan to your expected call volume, and browse supported RPC networks if your roadmap includes more than Ethereum.

Key Takeaways

• Ethereum mainnet uses chain ID 1, ETH with 18 decimals, and supports HTTP and WebSocket transport.
• Verify any endpoint with a single eth_chainId call before wiring it into your app.
• Production fintech workloads need archive access, trace methods, WebSocket support, burst handling, failover, and observability.
• Track confirmations with subscriptions plus a fallback poll rather than tight receipt polling.
• Most send failures are nonce or sequencing issues in your application, not the endpoint.
• Match the endpoint tier to your risk: public for prototypes, managed or dedicated for payment traffic.

Frequently Asked Questions

Can I use a public Ethereum RPC endpoint in production?

You can, but public endpoints are shared and typically come without support commitments. For payment flows, a managed RPC API or dedicated node gives you more predictable behavior and a clearer path to monitoring and failover.

What chain ID should a fintech app use for Ethereum?

Ethereum mainnet is chain ID 1. In wallet configuration files it is written as 0x1. Testnets use different chain IDs, so confirm the value matches the network you intend to transact on.

Do I need an archive node for reconciliation?

If you query balances or state at historical blocks, yes. A non-archive endpoint will fail on older block queries. Confirm archive support with your provider before relying on it for ledger backfills.

How do I monitor transaction confirmations efficiently?

Use a WebSocket subscription to newHeads and match incoming blocks against pending transactions. Keep a fallback poll so a dropped socket does not stall settlement detection.

What should I do if eth_sendRawTransaction keeps failing?

Check the nonce first. Re-read eth_getTransactionCount with the pending tag, confirm gas settings, and make sure only one service signs from a given address at a time. If nonces are correct, inspect the raw transaction encoding and chain ID.