What is an Ethereum API service and how do you choose one?

Decision guide: what to look for in an Ethereum API service

Before you compare providers, decide which workloads your Ethereum API service must support. A simple wallet frontend has different needs than a block explorer or a high-frequency trading bot. Ask yourself these questions:

• Do you need archive data? If you query historical state beyond the default pruning window, you need an archive node or an API service that offers archive data.
• Do you need trace methods? Tools like debug_traceTransaction and trace_block are essential for indexers and analytics, but not all providers expose them.
• Do you need WebSocket support? Real-time dApps rely on subscriptions like eth_subscribe to listen for new blocks and pending transactions.
• What is your request volume? Estimate peak requests per second. Public endpoints are rate-limited and unsuitable for production.
• Do you need dedicated resources? If you have strict latency or throughput requirements, a dedicated node gives you isolated capacity.

Once you answer these, you can filter providers by their feature set, pricing, and network coverage. For a quick start, OnFinality offers a managed Ethereum API service with public, dedicated, and archive options. Check the supported networks page to see which Ethereum networks are available.

What is an Ethereum API service?

An Ethereum API service is a hosted solution that provides access to Ethereum nodes via JSON-RPC. Instead of running your own node, you send HTTP or WebSocket requests to a provider's endpoint. The provider manages the underlying infrastructure, including synchronization, maintenance, and scaling.

Ethereum nodes expose a standard JSON-RPC interface. The most common methods include:

• eth_blockNumber – get the latest block number
• eth_getBalance – get the balance of an address
• eth_call – execute a read-only contract call
• eth_sendRawTransaction – broadcast a signed transaction
• eth_subscribe – subscribe to events via WebSocket

An API service typically adds value on top of raw nodes:

• Reliability: redundant nodes and failover
• Performance: load balancing and caching
• Data depth: archive data, trace methods
• Developer tools: dashboards, analytics, and key management

Ethereum API service vs. running your own node

Running your own Ethereum node gives you full control, but it comes with significant operational overhead. You need to provision hardware, sync the blockchain (which can take days), monitor uptime, and handle upgrades. For most teams, this is not a core competency.

An Ethereum API service offloads this complexity. You get a reliable endpoint without the DevOps burden. This is especially valuable for:

• Startups that need to move fast
• Teams with limited infrastructure expertise
• Applications with variable traffic that need to scale quickly

However, there are trade-offs. You depend on a third party for availability, and you may pay for usage. For teams with strict compliance or data sovereignty requirements, a dedicated node might be a better fit.

How to evaluate Ethereum API providers

When comparing Ethereum API services, consider these criteria:

OnFinality, for example, offers a managed Ethereum API service with public, dedicated, and archive options. You can find pricing details on the RPC pricing page.

Ethereum API service: public vs. managed vs. dedicated

There are three main tiers of Ethereum API services:

Public endpoints

Public endpoints are free and open to anyone. They are great for testing and low-volume development. However, they are rate-limited and not reliable for production. OnFinality provides a public Ethereum endpoint at https://eth.api.onfinality.io/public for experimentation.

Managed API services

Managed services provide a reliable, scalable API without you having to run nodes. They handle infrastructure, monitoring, and failover. This is the most common choice for production dApps. You pay based on usage or a subscription.

Dedicated nodes

Dedicated nodes give you exclusive access to a node instance. This offers the highest performance and isolation. It's ideal for high-throughput applications, indexers, or teams that need custom configurations. OnFinality offers dedicated Ethereum nodes through its dedicated node service.

How to connect to an Ethereum API service

Connecting to an Ethereum API service is straightforward. You typically get an endpoint URL and an API key (if required). Here's an example using curl to call eth_blockNumber:

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

For WebSocket subscriptions, you can use a library like ethers.js:

const { ethers } = require("ethers");

const provider = new ethers.WebSocketProvider("wss://eth.api.onfinality.io/public");

provider.on("block", (blockNumber) => {
  console.log("New block:", blockNumber);
});

Remember to replace the public endpoint with your own API key or dedicated endpoint in production.

Common pitfalls and troubleshooting

Even with a reliable API service, you may encounter issues. Here are common pitfalls and how to address them:

• Rate limiting: If you hit rate limits, consider upgrading to a paid plan or using a dedicated node.
• Timeouts: Long-running queries (e.g., eth_getLogs over a large range) may time out. Optimize your queries or use archive data.
• WebSocket disconnects: Ensure your client handles reconnection logic.
• Incorrect chain ID: When sending transactions, always set the correct chain ID (1 for Ethereum mainnet).
• Nonce errors: Use eth_getTransactionCount to get the correct nonce for an address.

For more detailed troubleshooting, refer to our RPC troubleshooting guide.

Key Takeaways

• An Ethereum API service provides reliable access to Ethereum data without running your own node.
• Evaluate providers based on network coverage, transport support, archive data, trace methods, and rate limits.
• Public endpoints are fine for testing, but production apps need managed or dedicated services.
• OnFinality offers a managed Ethereum API service with public, dedicated, and archive options.
• Always use the correct chain ID and handle WebSocket reconnections in your client code.

Frequently Asked Questions

What is the difference between an Ethereum API service and an RPC provider?

An Ethereum API service is essentially an RPC provider. They both expose JSON-RPC endpoints for interacting with the Ethereum blockchain. The term "API service" may imply additional features like analytics or data indexing, but the core is the same.

Can I use a public Ethereum endpoint for production?

Public endpoints are rate-limited and not reliable for production. They are suitable for development and testing only. For production, use a managed API service or a dedicated node.

Does OnFinality support Ethereum archive data?

Yes, OnFinality offers archive node options for Ethereum. You can find more details on the Ethereum network page and the pricing page.

How do I get an API key for OnFinality's Ethereum API service?

You can sign up on the OnFinality platform and create an API key from the dashboard. The key is used to authenticate requests to your dedicated or managed endpoints.

What is the public Ethereum endpoint for OnFinality?

The public endpoint is https://eth.api.onfinality.io/public. It's for testing and development; for production, you should use a dedicated or managed endpoint with your API key.