Public RPC Nodes: Free Endpoints vs Production Infrastructure

Public RPC Nodes Decision Checklist

Before you rely on a public RPC node, consider these criteria:

Criterion	What to check	Why it matters
Rate limits	Does the provider publish limits? Test with a high-frequency call.	Exceeding limits causes 429 errors and dropped requests.
Uptime SLA	Is there a published uptime guarantee? Check recent status pages.	Production apps need consistent availability; free endpoints often have no SLA.
Data freshness	Is the node lagging behind the chain tip? Compare block height.	Stale data can lead to failed transactions or incorrect state reads.
Supported methods	Does it support eth_call, eth_getLogs, trace_*, or WebSocket?	Archive data and real-time subscriptions require specific endpoints.
Security & privacy	Does the node log requests or inject ads? Check privacy policy.	Sensitive transaction data may be exposed; some public nodes inject MEV.
Geographical coverage	Where are the servers located?	Latency increases with distance; limited regions affect global users.

What Are Public RPC Nodes?

A public RPC node is a blockchain node that is open for anyone to send remote procedure call (RPC) requests. These nodes are typically operated by blockchain foundations, community members, or commercial providers offering a free tier. They allow developers to read blockchain data (e.g., account balances, transaction receipts) and write transactions without running their own node.

Public RPC endpoints are the most accessible way to interact with a network. For example, Ethereum has a default public endpoint at https://eth-mainnet.public.blastapi.io, and many other chains provide similar URLs. However, because these endpoints are shared among all users, they impose strict rate limits and can become unreliable during traffic spikes.

How Public RPC Nodes Work

Under the hood, a public RPC node runs one or more blockchain client software (e.g., Geth for Ethereum, solana-validator for Solana). It listens for incoming HTTP or WebSocket connections, interprets JSON-RPC requests, and returns the appropriate data from its local copy of the blockchain.

Here's a simple example of querying the current block number using a public Ethereum RPC endpoint:

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

Expected response:

{"jsonrpc":"2.0","id":1,"result":"0x1345abc"}

Common Pitfalls of Public RPC Nodes

• Rate limiting: Most public nodes allow only a few requests per second. High-throughput dApps will quickly hit these caps.
• Unreliability: Public endpoints can go offline without notice. They are often community-run and may not have redundancy.
• Stale data: Some public nodes are not kept fully synced, returning out-of-date information.
• Security risks: A malicious node could censor transactions or return manipulated data. Always verify critical reads across multiple sources.
• No support: If something breaks, you're on your own. Public nodes rarely offer support channels.

When to Use Public RPC Nodes

• Prototyping and development: Quick testing on testnets (e.g., Sepolia, Goerli) where data loss is acceptable.
• Low-traffic dApps: Applications with fewer than 1,000 daily users can often survive on public endpoints.
• Read-only operations: Browsing wallet balances or fetching token metadata where latency isn't critical.
• Hackathons and MVPs: Speed of deployment outweighs reliability concerns.

When to Upgrade to Private or Dedicated RPC

• Production applications: Any app serving real users needs consistent uptime and predictable performance.
• High throughput: DeFi protocols, NFT marketplaces, and gaming apps often require thousands of requests per second.
• Archive data: Historical state lookups (e.g., eth_getBalance for old blocks) require an archive node, which public nodes seldom provide.
• Trace and debug methods: trace_block, debug_traceTransaction are typically only available on private endpoints.
• WebSocket subscriptions: Real-time event listeners need a persistent connection that public nodes often disconnect.
• Privacy: If you don't want your app's traffic pattern shared, a private endpoint is safer.

For these cases, consider a managed RPC service like OnFinality, which offers dedicated nodes and premium shared endpoints with higher rate limits, global coverage, and support. Check the RPC pricing and supported networks for details.

How to Evaluate Public RPC Providers

If you choose to use a public node, evaluate providers based on:

• Transparency: Does the provider list its rate limits, uptime history, and server locations?
• Performance: Run a simple latency test from multiple regions. Use tools like curl -w "%{time_total}" or dedicated benchmarking scripts.
• Chain support: Ensure the provider supports the networks you need (mainnet, testnets) and the RPC methods your app relies on.
• Ad-free: Some public nodes inject ads or redirect requests. Avoid those for production use.

Key Takeaways

• Public RPC nodes are free but come with significant limitations: rate caps, no SLAs, and potential security risks.
• They are suitable for development, low-traffic apps, and testnets.
• For production, high-throughput, archive, or real-time needs, you should upgrade to a private or dedicated RPC solution.
• Always test a public provider thoroughly before depending on it, and have a fallback plan.
• OnFinality provides reliable dedicated nodes and premium shared endpoints across 80+ networks with transparent pricing and support.

Frequently Asked Questions

Q: Are public RPC nodes safe to use for transactions?
A: They can be used for sending transactions, but the node may see the raw transaction data. For sensitive operations, consider using a private endpoint or a dedicated node.

Q: What's the difference between public and private RPC?
A: Public RPC endpoints are shared among all users and have strict rate limits. Private endpoints are dedicated to a single user or organization, offering higher limits, better performance, and often additional features like archive data.

Q: How do I find public RPC endpoints for a specific network?
A: There are directories like Chainlist.org, PublicNode.com, or CompareNodes.com that list endpoints. OnFinality also offers public endpoints for many testnets; see the networks page for details.

Q: Can I use public RPC for a production NFT mint?
A: It's risky. High traffic during mints can trigger rate limits and drop requests, leading to failed transactions. A dedicated node is strongly recommended.

Q: Does OnFinality offer public RPC nodes?
A: OnFinality provides free public endpoints for several testnets and limited mainnet access. For production, we recommend our professional plans with higher rate limits and dedicated node options.

Related resources

• How to Choose an RPC Provider
• RPC Pricing
• Supported Networks

Originally published at OnFinality.