Summary
Avalanche is a high-throughput Layer 1 blockchain platform with a multi-chain architecture. Developers interact with Avalanche via JSON-RPC endpoints for the Contract Chain (C-Chain), Platform Chain (P-Chain), and Exchange Chain (X-Chain). This guide provides the official endpoint URLs, chain IDs, and a practical decision checklist to help you select a reliable Avalanche RPC provider for your project.
Avalanche RPC Decision Checklist
Before integrating an Avalanche RPC endpoint, consider the following:
- Which chain do you need? C-Chain (EVM-compatible smart contracts), P-Chain (validator/subnet management), or X-Chain (asset transfers)?
- Mainnet or testnet? Use Fuji testnet for development and testing.
- Public vs. private RPC? Public endpoints are rate-limited and may be unreliable for production. Private endpoints offer higher rate limits and dedicated resources.
- Do you need archive data? Archive nodes provide historical state access for analytics or dApps that query past blocks.
- WebSocket support? For real-time subscriptions (e.g., pending transactions), ensure the provider supports WebSocket endpoints.
- Geographic distribution? Low latency requires endpoints close to your users or infrastructure.
Avalanche Network Architecture
Avalanche consists of three built-in blockchains, each with its own RPC interface:
- C-Chain (Contract Chain): EVM-compatible, runs smart contracts. Uses standard Ethereum JSON-RPC methods.
- P-Chain (Platform Chain): Coordinates validators, manages subnets, and staking. Has its own set of API methods.
- X-Chain (Exchange Chain): Handles creation and transfer of digital assets (e.g., AVAX). Uses Avalanche-specific APIs.
Additionally, Avalanche supports subnets — custom blockchains with their own validator sets and virtual machines. Each subnet has its own RPC endpoint.
Avalanche RPC Endpoints
Mainnet
| Chain | RPC Endpoint (HTTP) | WebSocket Endpoint | Chain ID |
|---|---|---|---|
| C-Chain | https://api.avax.network/ext/bc/C/rpc |
wss://api.avax.network/ext/bc/C/ws |
43114 (0xa86a) |
| P-Chain | https://api.avax.network/ext/bc/P |
Not publicly available | — |
| X-Chain | https://api.avax.network/ext/bc/X |
Not publicly available | — |
Fuji Testnet
| Chain | RPC Endpoint (HTTP) | WebSocket Endpoint | Chain ID |
|---|---|---|---|
| C-Chain | https://api.avax-test.network/ext/bc/C/rpc |
wss://api.avax-test.network/ext/bc/C/ws |
43113 (0xa869) |
| P-Chain | https://api.avax-test.network/ext/bc/P |
Not publicly available | — |
| X-Chain | https://api.avax-test.network/ext/bc/X |
Not publicly available | — |
Note: The public API nodes (
api.avax.network) have rate limits and may not be suitable for production workloads. For production, consider a dedicated RPC provider like OnFinality, which offers higher rate limits and dedicated nodes.
How to Choose an Avalanche RPC Provider
When evaluating RPC providers for Avalanche, use the following criteria:
| Criterion | What to check | Why it matters |
|---|---|---|
| Endpoint coverage | Does the provider support C-Chain, P-Chain, X-Chain, and Fuji testnet? | You may need multiple chains for your dApp. |
| Rate limits | What are the requests per second (RPS) limits? | Public endpoints often throttle; production apps need higher limits. |
| Uptime and reliability | Is there a service-level agreement (SLA)? | Downtime can break your application. |
| Latency | Where are the nodes geographically located? | Lower latency improves user experience. |
| Archive data | Does the provider offer archive nodes? | Needed for historical queries and analytics. |
| WebSocket support | Are WebSocket endpoints available? | Required for real-time updates. |
| Pricing model | Pay-as-you-go, subscription, or free tier? | Choose based on your budget and usage patterns. |
For a deeper dive, see our guide on how to choose an RPC provider.
Making RPC Calls to Avalanche C-Chain
Since the C-Chain is EVM-compatible, you can use standard Ethereum libraries like ethers.js or web3.js. Below is an example using curl and ethers.js.
Using curl
curl -X POST https://api.avax.network/ext/bc/C/rpc \
-H "Content-Type: application/json" \
-d '{
"jsonrpc": "2.0",
"method": "eth_blockNumber",
"params": [],
"id": 1
}'
Using ethers.js
const { ethers } = require("ethers");
const provider = new ethers.JsonRpcProvider("https://api.avax.network/ext/bc/C/rpc");
async function getBlockNumber() {
const blockNumber = await provider.getBlockNumber();
console.log("Current block number:", blockNumber);
}
getBlockNumber();
WebSocket Subscription Example
const { WebSocket } = require("ws");
const ws = new WebSocket("wss://api.avax.network/ext/bc/C/ws");
ws.on("open", function open() {
ws.send(JSON.stringify({
jsonrpc: "2.0",
method: "eth_subscribe",
params: ["newHeads"],
id: 1
}));
});
ws.on("message", function incoming(data) {
console.log("New block:", JSON.parse(data));
});
Common Pitfalls and Troubleshooting
1. Rate Limiting
Public endpoints often return 429 Too Many Requests. Switch to a private RPC provider with higher limits.
2. Incorrect Chain ID
Ensure your wallet or dApp uses the correct chain ID: 43114 for mainnet, 43113 for Fuji testnet.
3. WebSocket Not Supported on P-Chain/X-Chain
Only the C-Chain supports WebSocket connections on the public API. For other chains, use HTTP polling.
4. Method Not Found
Some Ethereum methods (e.g., eth_getLogs) are supported on C-Chain but not on P-Chain or X-Chain. Check the AvalancheGo C-Chain RPC documentation for the full list.
Next Steps
- Explore supported RPC networks to see which chains OnFinality supports.
- Review RPC pricing for free and paid plans.
- For production workloads, consider a dedicated node for predictable performance.
Key Takeaways
- Avalanche has three main chains: C-Chain (EVM), P-Chain (platform), and X-Chain (assets).
- Public endpoints are suitable for testing but not for production due to rate limits.
- Choose a provider based on endpoint coverage, rate limits, latency, and archive support.
- Use standard Ethereum tools for C-Chain development; P-Chain and X-Chain require Avalanche-specific APIs.
- Always verify chain IDs and WebSocket availability before integrating.
FAQ
What is the Avalanche C-Chain RPC URL?
The mainnet C-Chain RPC URL is https://api.avax.network/ext/bc/C/rpc. For Fuji testnet, use https://api.avax-test.network/ext/bc/C/rpc.
Does Avalanche support WebSocket RPC?
Yes, the C-Chain supports WebSocket at wss://api.avax.network/ext/bc/C/ws (mainnet) and wss://api.avax-test.network/ext/bc/C/ws (testnet).
What is the chain ID for Avalanche C-Chain?
Mainnet chain ID is 43114 (0xa86a). Fuji testnet chain ID is 43113 (0xa869).
Can I use Ethereum libraries with Avalanche?
Yes, the C-Chain is fully EVM-compatible, so you can use ethers.js, web3.js, Hardhat, and other Ethereum tools.
Where can I find a reliable Avalanche RPC provider?
OnFinality provides Avalanche RPC endpoints with higher rate limits and dedicated node options. Check our supported networks page for details.
FAQ
What is the Avalanche C-Chain RPC URL?
The mainnet C-Chain RPC URL is https://api.avax.network/ext/bc/C/rpc. For Fuji testnet, use https://api.avax-test.network/ext/bc/C/rpc.
Does Avalanche support WebSocket RPC?
Yes, the C-Chain supports WebSocket at wss://api.avax.network/ext/bc/C/ws (mainnet) and wss://api.avax-test.network/ext/bc/C/ws (testnet).
What is the chain ID for Avalanche C-Chain?
Mainnet chain ID is 43114 (0xa86a). Fuji testnet chain ID is 43113 (0xa869).
Can I use Ethereum libraries with Avalanche?
Yes, the C-Chain is fully EVM-compatible, so you can use ethers.js, web3.js, Hardhat, and other Ethereum tools.
Where can I find a reliable Avalanche RPC provider?
OnFinality provides Avalanche RPC endpoints with higher rate limits and dedicated node options. Check our supported networks page for details.
Related resources
Originally published at OnFinality.
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